Chemistry (Pool Geeks Only)
Water Chemistry Basics
Water chemistry is the most important and least understood phase of pool or spa care. It can be complex and confusing, but it can be simplified. There are many variables in water we must contend with. By using common sense and basic reasoning after you learn the basics, you can become an expert. No Ph. D. in water chemistry is necessary; but many hours of on-the-job training are needed. Knowing the water in your area and the mineral concentration is a must. Pool owners can find out what mineral concentrations are in their water supply by calling their local water department. Professionals should be able to test for these and have the proper test kits needed. Once you determine the quality of the supply water, you can determine the basic sanitizers needed to make balancing easier. Before I start up new services, I test water for water hardness, cyanuric acid, total dissolved solids (TDS), pH, and total alkalinity (TA). I can then determine if I must change the water, or at least some of it. A professional should have a basic 4-in-1
test kit, plus the DPD for combined chlorine, CYA, water hardness, and TDS meter. A test kit for copper and iron should also be considered. If you intend to service commercial, municipal, or even semi- commercial pools, you should consider one of the Oxygen Reduction Potential (ORP) testers. The inexpensive ones I have tried did not give a true reading, and are evidently not calibrated for the lower chlorine concentrations used in residential pools. Even with a 4.0 chlorine reading, the ORP tester did not show in the range it required for enough sanitizer. Do not rely on the OTO chlorine tests, as these are not for combined chlorine, but for total chlorine only. Use the DPD tests to determine combined chlorine. You can buy combination test kits with most of the needed tests, or they can be purchased separately. I use a kit that has free available chlorine, combined chlorine, total chlorine, pH, acid demand, base demand, cyanuric acid, total alkalinity, and water hardness. I also have a TDS meter and a
kit for copper and iron.
Contrary to what many experts write on balancing water, I start with the water hardness. This is the calcium and magnesium concentrations in water. Higher concentrations of these can provide scale formation; lower concentrations can have corrosive tendencies. The range of water hardness can determine where total alkalinity should be maintained. If the water has higher water hardness, maintain a lower total alkalinity range; for lower water harness, maintain a higher TA range. This allows a buffer zone between the corrosive and scaling tendencies of water. Plus, TA in proper range can help maintain pH range much more easily. Most experts refer to this buffering zone, or area, as the saturation point or index. Refer to Langelier index on this. Regardless of the formula or method you use, water hardness will play an important part. I prefer water hardness in the 200-400 ppm range. This is considered moderate, if not ideal. In this area, it is easier to maintain TA and, down the line pH. If below 200 ppm,
chemicals can be added to raise the water hardness. If above 600 ppm, change the water (if supply water has water hardness lower than this, it can lower total water hardness).
Total Alkalinity (TA)
This is the amount of alkaline materials in the water. Lower or higher TA can give us the same scaling or corrosion as low or high water hardness. The TA acts as the stabilizer or a buffer for the pH. Here again, sanitizers will play an important role in maintaining these ranges according to the pH factors of the sanitizers. I use high pH liquid chlorine along with low pH trichloro tablets, and prefer my TA in the 90-130 ppm range. Our local supply water has an average 200-250 ppm water hardness, 7.7 pH, and TA around 150 ppm. These concentrations can and will often vary from one water source to another, and often only a few miles apart. Some experts recommend lower TA, others according to the sanitizers and their pH factors, lower pH factors, higher TA, and vice versa. But if you combine several sanitizers, as most of us do, then we have another ball game. If TA is lower or higher than the recommended range, you can have difficulty keeping the pH in the recommend range.
pH is in reference to the acidic or alkaline properties of materials in water. A pH of 7.0 is neutral; above 7.0 is alkaline; below 7.0 is acidic. With my water supply’s concentrations in the range mentioned earlier, I maintain a pH of 7.4-7.6- the middle of the pH scale- and the range recommended by most experts (7.2-7.8). Here again, water hardness can determine if you will use the lower end of the scale (7.4-7.2 for higher water hardness), the higher end (7.4-7.8 for lower water hardness), or somewhere within this range. Test water hardness at least every six months; if it is higher than average route, compensate by slightly lowering TA and slightly lowering the pH range. If above 600 ppm, consider changing some or all of the water. If this is not possible, consider using a calcium inhibitor to hold the calcium in solution to reduce or prevent scale formation. Too many service pros do not test water hardness often enough and don’t compensate for higher water hardness when they maintain TA or pH
ranges. Low pH, as well as low TA and low water hardness, can contribute to corrosive tendencies directly, and can cause staining damage to equipment (plaster, vinyl, and fiberglass). Higher ranges of these can cause scale formation in heater, plumbing, and filter equipment. Chlorine is more effective as a sanitizer if the ranges above are in the recommended areas. Test for water hardness at least twice each year, and compensate for higher concentrations if water is not changed.
Total Dissolved Solids (TDS)
Total dissolved solids are the combined organic and inorganic minerals in water. These consist of the residue from the chemicals we add, as well as from other sources. Dirt, soap, leaves, iron, other metals, and anything introduced into the water anywhere along the way. Higher concentrations of these can be bad news. High TDS can slow down the killing power of the sanitizers, can cause more problems controlling algae, promote scale formation, and even give a false pH reading. According to experts, safe levels of total dissolved solids; (TDS) can vary. However most agree that if the TDS count is above 2000 ppm present in your fresh water prior to the use of this water in your swimming pool, this thought accepts that we know that TDS will naturally increase the longer the water exists in the swimming pool. The only way to reduce the TDS levels in the swimming pool is to remove and replace the water; this represents the scientific principal of saturation transference. While water in the pool is
evaporating, only the fresh water is evaporating, the components of the total dissolved solids will never evaporate; these solids will remain in the water and continue to increase. So, if you do change water to reduce the TDS, change at least 25%, as make-up water from splashing or evaporation added is not going to reduce these concentrations, only add to them. Spa and hot tub water should be changed often to reduce the TDS.
Sanitizers’ Contributions to TDS
If we can change water as often as needed to significantly reduce the TDS, then the percentages each of the sanitizers can add to these build ups is not that critical. But in areas with water shortages or the potential for them, then we should know this information and use sanitizers that contribute the least. Following is a quote from the June 22, 1990, issue of the Service Industry News. The additional chemicals needed along with these to balance or compensate for the higher of lower pH factors of each sanitizer is included in the percentages.
“Basic chemicals used for chemically treating and balancing pool water and spa water (national average): Bromide salts (sodium bromide), 8 ppm; bromine tablets, 10 ppm; calcium hypochlorite, 9 ppm; liquid chlorine (sodium hypochlorite), 20 ppm; gas chlorine, 20 ppm; dry acid (sodium bisulfate), 8ppm; lithium hypochlorite, 9 ppm; trichloro, 10 ppm; dichloro, 8ppm; sodium bicarbonate, 8 ppm; soda ash, 8 ppm; sodium sesqui, 8 ppm, cyanuric acid, 8 ppm, non-chlorine shock (potassium monopersulfate), 8 ppm.”
All this good information we cannot learn on this route. I appreciate the efforts of the people who publish these facts that those of us in the service industry need. I find more publications are now more service minded, and we are finally receiving the respect we deserve. All water is not fresh; it will contain many variations of minerals and materials. Test your pools and spas often. As dissolved solids and water hardness build up, change some water if possible. If not, then consider using a sanitizer that can contribute the least to these build ups.
Water - How Much?
Once you fully understand the testing procedures and balance ranges, next is to know the amount of water in pools, spas, and hot tubs. Most sanitizers and other chemicals you will use are formulated for a certain number of gallons of water. If you do not know how much water, then you do not know how much sanitizer or whatever to add to do the job properly. Pool owners/store customers are bad news when it comes to trying to find out how much water is in their pool. They may have a 16,000 gallon pool, but they tell you it holds up from 1,500 to 30,000 gallons. We do not have to be exact on the number of gallons, but we must have a reasonably close estimate. Below are basic formulas to use in determining at least approximate volumes of water:
Rectangular: Multiply the length, times the width, times the average depth, times 7.5.
Example: 15’ X 30’ pool, approximately 5’ average depth
15 X 30 X 5 X 7.5= 16,875 gallons
Round: Multiply the diameter, times the diameter, times the average depth, times 5.9.
Oval: Multiply the maximum length, times the maximum width, times the average depth times 5.9.
Follow the same procedures as above, but allow for steps and benches.
4’ round X 3’ deep=250 gallons
4’ round X 4’ deep=350 gallons
5’ round X 4’ deep=500 gallons
6’ round X 4’ deep=750 gallons
Liquid Chlorine (Sodium Hypochlorite)
This is the most widely used sanitizer for pool water treatment. It is one of the fastest and least expensive chlorines- fast acting, excellent germicide, algaecide, bactericide, and disinfectant. These are the positive factors. But it also has a high pH (13), a shorter shelf life, and is heavy and bulky. For each gallon we add, we contribute up to 20 ppm TDS. Still, the positive factors outweigh the negative ones for pool water treatment (higher pH, contains caustic soda, and salt). This is not recommended for spas, hot tubs, or smaller pools. In areas with higher pH, TA, and water hardness, I use and recommend, along with the liquid chlorine, a lower pH sanitizer. I use the trichloro tabs in floaters or in automatic chlorinators. This combination of both high and low pH factors sanitizers can help maintain the recommended ranges of pH and TA. Liquid chlorine is not stabilized; if it is used in pools exposed to the ultraviolet rays of sunlight, it may be necessary to add cyanuric acid. In enclosed
pools or covered pools with no cyanuric acid in the water, liquid chlorine is more effective as a sanitizer. If surrounded by CYA or higher calcium or TDS concentrations, all chlorine is much less effective than if allowed to be more unstable and react with changes in the pH and TA. This is why we maintain these in the recommended ranges-liquid chlorine 10-12.5% per gallon=available chlorine.
This is available in granular and tablet form. It is also popular sanitizer for pools. It has a high pH (11.8), TDS 9 ppm, contains calcium and can raise calcium hardness, and can leave a visible residue in the pool bottom. In areas with lower calcium hardness, pH, and TA in the water supply, this type of sanitizer should be considered as basic sanitizer, as it can help raise these and make balancing the water easier. It is not recommended for spas and hot tubs, due to the higher pH and higher calcium content: 65% available chlorine, not stabilized. Should be dissolved before adding.
This is granular chlorine with a pH factor of 10.7 and a TDS of 9 ppm. It dissolves instantly and is not stabilized; used effectively as a shock treatment in pools and spas, 35% available chlorine. Safer to store than some other types of dry chlorines. I alternate the use of this with non-chlorine shock and bromine tablets in floaters for spas and hot tubs. With higher pH factor, it helps compensate for low pH factor bromine. Safer for vinyl and fiberglass pools, as it dissolves instantly and does not need dissolving, only in colder water.
This is stabilized granular chlorine with near neutral pH factor and approximately 56% available chlorine. But I do not fully understand these percentages, as the stabilizer content is over 50%. So we assume that dichloro chlorines are approximately 56% stabilized chlorines. I wish the manufacturers of these would explain this more clearly, but I have been unable to find any answers from my local suppliers or sources. 56% chlorine and 55% stabilizer cannot give the amounts of actual available chlorine. But dichloro, being near neutral and stabilized, is popular as a basic sanitizer for smaller pools, spas, and hot tubs-pH factor is around 6.8 and TDS is 8 ppm. For use in spas and hot tubs, or in pools that are exposed to direct sunlight. Most spas and hot tubs are covered to retain heat and do not need stabilized chlorine, as sunlight is not a factor. I do not sell or recommend stabilized chlorines if they are not needed. In smaller pools that are exposed to sunlight, the dichloro stabilized chlorines
can be effective basic sanitizers, and their near-neutral pH factor should be considered. If using any stabilized chlorines, I recommend that you test conditioner levels often, as these can bring the CYA above the recommended ranges. I test my own pool services once each month.
These stabilized chlorines are available in granular and tablet form. They have a low pH factor (below 3) and TDS factor of 10 ppm. The granular form is often used as an algaecide for advanced stages of black algae. Due to the low pH factor, the pump should not run and 48 hours or more are required before swimming is allowed. In most instances, pH and TA must be raised after the trichloro granular is used. Here again, I see a possible controversy as to the exact amounts of available chlorine in trichloro tablets. The container reads: “Active Ingredients: Trichloro-s-Triazintrone=99%; Inert Ingredient= 1%. Available chlorine 99%” but with over 50% stabilizer, where are we as to actual available chlorines? If anyone can give me these answers, please do so. I use trichloro tablets in floaters on my services, along with liquid chlorine. The lower pH of trichloro helps maintain a lower pH. But being stabilized, I test CYA every 30 days. If the CYA is above 80 ppm, I stop using stabilized chlorine and use
more liquid or change some water to lower the CYA. Due to low pH and high chlorine in thrichloro tablets; do not add to the skimmer. This can damage plumbing filter and heater and cause stains. This strong corrosive harsh solution can remove the chemicals in plastics that allow pliability and flexibility. Plastics can become brittle and break or become susceptible to damage if exposed to this solution over a period of time.
This is used mostly as a sanitizer for larger municipal pools where a higher, more constant chlorine level must be maintained due to much more traffic. It can also be used in residential pools. Gas chlorine is not stabilized; it has a very low pH of 1.0, and a TDS factor of 20 ppm. It can be dangerous to handle and store, and should be used only by trained professionals. It is much less expensive than other chlorines, but because it is corrosive and possibly dangerous for average pool service professionals to handle, few of us use it.
Bromine is a popular and effective sanitizer for spas and hot tubs that are covered most of the time to reduce heat loss and evaporation. Bromine cannot be stabilized with cyanuric acid. If exposed to direct sunlight, the ultraviolet rays can remove bromine rapidly. Bromine can have several advantages over chlorine. It is not dependent on pH, as chlorine is. Combined bromine (bromamines) are effective sanitizers; chloramines are not. Bromine tablets dissolve more slowly than trichloro tablets, and in buffered water bromine has a higher pH. A sodium bromide bank is necessary if changing over to bromine from chlorine. An erosion-type automatic feeder or, in residential spas, bromine floaters, are recommended. Many experts prefer bromine for spas and hot tubs. In buffered balanced water, bromine has a pH of around 7. Trichloro chlorines have lower pH. This can allow an easier pH and total alkalinity range. pH range recommended is 7.5. According to the experts, total alkalinity ranges can vary, but 100-150
ppm TA is most often recommended. pH and total alkalinity ranges often vary according to the pH of the sanitizer used.
If changing over from chlorine to bromine, and the water has any trace of cyanuric acid (conditioner), all water should be removed and replaced with fresh water. Cyanuric acid disrupts the sanitizing properties of bromine, as bromine tends to attack the cyanuric acid and is less effective as a sanitizer. Maximum conditioner level using bromine is 10 ppm. If bromine-treated water needs chlorine, do not use stabilized chlorines. When chlorine is needed, I prefer the non-stabilized, fast-dissolving lithium hypochlorite. It has a pH factor of 10.7. With bromine around 7, lithium added as needed can help maintain proper pH and total alkalinity ranges.
This is a non-chlorine oxidizer used to remove excessive amounts of nitrogen and ammonia compounds. It also activates bromine from tablets and the sodium bromide bank if it drops below recommended levels. Bromine contains chlorine that allows a continual release of active bromine; but if non-chlorine oxidizers are added, too often they can remove the chlorine residual that is needed to help bromine do its job effectively.
My own theory, if using bromine, is to alternate oxidizers every other time bromine is activated. Once use a non-chlorine oxidizer and the next time add the lithium chlorine. This procedure can offer better, safer water with more constant chlorine residual needed to activate the bromine effectively.
If using chlorine only as a basic sanitizer, breakpoint chlorination or super-chlorination must be used to remove the chloramines. Bromine-treated water virtually eliminates this procedure. Bromine absorbs and uses most of the chlorine. Adding lithium and potassium monopersulfate as needed should remove excessive buildups of nitrogen and ammonia compounds, without needed super chlorination. Recommended balance ranges using bromine: ph 7.4-7.6, TA 100-150 ppm, calcium hardness 200-400 ppm, bromine 2-4 ppm. Combined bromine is an effective sanitizer, unlike combined chlorines, and the total bromine residual, not free available, is considered when ppm is maintained.
These consist of millions of tiny particles that are too light to settle to the bottom and too small to be trapped by the filter. They can cause a hazy or cloudy appearance. By using a sequestering agent (clarifier) we combine these so the filter can remove them. These may not be a problem as far as water balancing, but we need clear, sparkling water, and we can control and remove suspended solids.
Contrary to the belief of many pool owners, adding make-up water does not eliminate the need to change water. Adding make-up water does not remove CYA or mineral buildups, including calcium concentrations. Only the pure water evaporates, leaving behind minerals that will continue to build up. We need to teach pool owners this good information.
Changing water should be done if possible when CYA, water hardness, and TDS concentrations are higher than recommended. At least enough water should be changed to significantly reduce these concentrations. Don’t set up the pump yet – look before you leap! In areas with high water tables and certain soil conditions, draining a pool can cause big problems, and you could be liable. Even gunite plastered pools can float up if soil conditions are just right (or just wrong!). If in doubt, find out. If you are not familiar with soil conditions and you intend to drain a pool, ask a local, experienced pro who services in that area about any problems with draining pools. Some pools have a special hydrostatic valve to equalize potential problems and save you a heap of trouble. Work with a local pro in that area if you are in any doubt. Do not overextend. There are too many jokers out there now that will try anything to make a buck. They don’t last long, but they are out there.
Fiberglass Pools: Never drain fiberglass pools completely. These can either pop out of the ground, or the sides can collapse. If a fiberglass pool must be completely drained, have a local fiberglass pool builder do this, as special braces may be needed. In most instances – but don’t say old Harv told you so – you can drain 25%, refill, and repeat as needed.
Vinyl Pools (In Ground or Above Ground): Never drain these completely unless you are an expert on this type of pool. Completely drained vinyl can shrink. It can move and may not fit properly when refilled. I recommend draining no more than 75% of the water. Leave the bottom well covered with water.
Plastered Pools: In my area, I have drained well over 1,000 pools in my time and never ever had a problem. In most instances, I drain plastered pools completely. Occasionally, if the CYA is too high and TDS is not too high and the plaster doesn’t need acid or chlorine washing, I will pump out 60% of the water to reduce CYA or TDS. But, if you are not familiar with your area’s water tables or soil conditions, find out from local pros before you plug in your pump. Never leave a plastered pool empty any longer than necessary to wash or repair it. Plaster can lift off the gunite if exposed very long to sunlight. Many pool owners learn this the hard way, when the pool plaster is extensively damaged from leaving it empty too long – they have to pay for re-plastering or live with the damaged plaster. Many years ago, I installed dozens of replacement liners for in-ground vinyl pools. After all this, I even tried occasionally to acid wash these. But I wised up. On these types, calcium
and dirt can plug smaller pinholes and reduce or even completely stop the vinyl pool from leaking. But when the vinyl was acid washed, I removed the calcium from these pinholes and the pool started leaking again. I had to patch these – free, gratis – so learn from my mistakes, don’t make your own! Not being an expert on fiberglass pools, I do not attempt to repair or drain them. I leave this to the people that sell and install them. But there are good people out there who have all the knowledge necessary to specialize in vinyl and fiberglass pools. Chemicals for vinyl and fiberglass pools will be covered later in this manual. Even if you prefer a certain type of pool, don’t run the others down, as many pool owners have these and are very satisfied with them. I have several in-ground vinyl pools on service; on these I have a suction-side automatic pool cleaner, because vacuuming these manually with brush-type vacuum heads requires too much of my time. If you service vinyl or fiberglass pools, try to sell
them an automatic pool cleaner. This will reduce their monthly service and save you time.
After learning how and when to test, next you must arrive at the balance ranges you will need to maintain for your pools. Contrary to what you may hear or read, I start with water hardness, not pH; next is total alkalinity. The water hardness range will determine where you should keep the TA and the pH range – high water hardness, slightly lower TA. Lower water hardness, slightly higher TA. This gives a buffer area or zone, and allows for less chance of water balances being off. If acidic or alkaline chemicals or materials are added to the water, we will have a little breathing room. Again, I stress the importance of knowing all the concentrations in the supply water and the pool water you will chemically treat. All pools will not have fresh water and lower concentrations of these, so each pool should be tested and go from there. Water hardness in the 200-400 ppm range is easier to keep balanced than are higher or lower concentrations. I consider this a moderate range or concentration. If you read this
and think old Harv is getting technical and confusing with his recommendations, no way – if this old high school dropout can do it, you can do it! Spend more time out there with your test kits and less time watching the T.V. game shows or soaps. With water in the 200-400 ppm water hardness range, I try to maintain a TA of 90-120 ppm and a pH of 7.4-7.6. If water hardness is below 200 ppm, bring it up by adding calcium chloride. Read the instructions on the container regarding how much is needed and how to add it. I never have water hardness in my area below 250 ppm.
If water hardness is above 600 ppm, I change enough water to lower this to where I can live with it. If water hardness is 400-600 ppm, I use slightly lower TA and pH ranges. Some areas may have lower or higher concentrations. Sanitizers and their pH factors must always be considered. Lower water hardness uses sanitizers with higher pH factors; and the opposite with higher water hardness. Normally, TA will be lower if water hardness is lower, and the opposite; but this is not always the case. We must try to balance TA before we balance pH. For high TA, try adding muriatic acid in one or two areas in the deep end. To lower pH, try diluting muriatic acid at least three parts water to one part muriatic acid. I use a gallon plastic bottle and pour this diluted solution slowly all around the pool- not near the steps, love seats, or light. Be careful not to splash this on the decking or on your feet or clothing. These variations should be considered, as they do work for me. How or why they work requires a
technical explanation or theory that I do not understand. If you follow the chart below and keep all the above information in mind, then with hard work and a good investment of time, you can become an expert, write manuals, and stop cleaning those dirty pools.
xx ph xx
90-120 ppm pH 7.4-7.6
60-90 ppm pH 7.2-7.4
I use liquid chlorine and trichloro as basic sanitizers.
The chart above gives us a ball park figure to shoot at, but there are many variables to consider, including the pH factors of your basic sanitizers and water temperature. I use an average of 66° for my area. I do not contend with either high or low water hardness in my area supply water, and can change water as needed to lower calcium hardness. Consider all the variables in your supply water before arriving at the ranges you will maintain. Also consider the pH factors of the sanitizers you will use.
These were formulated to be used along with basic sanitizers to reduce scaling and staining and for sparkling, easier to chemically balance and treat pool and spa water. These are the calcium and metal inhibitors –chelating or sequestering agents that can hold the calcium, copper, iron, and other metals in solution, prevent them from precipitating out into a solid form, and prevent or reduce scale formation or metal staining. Others are used to clump the suspended solids together so the filter can trap and remove them from sparkling water. Reactive silicones break up the surface tension of water to stop foaming. Silicone emulsions which protect fiberglass finish and algaecides are often considered along with basic sanitizers as special additives. In the hotter water of spas and hot tubs with more scaling and staining tendencies, with higher chlorine or bromine levels needed and more aggressive water, specialty chemicals are considered a must. Here again, we must know when and how to use these as sunlight, higher chlorine
levels, lower or higher pH and TA ranges, and filtration can remove them. These can do all the good things mentioned, but they will not stay and work forever and can drop out. Adding these weekly or semi- weekly may be needed if the water has high calcium, copper, or metal concentrations. In spas it should be part of the regular weekly maintenance. For higher calcium concentrations, use calcium inhibitors. For high copper or iron levels, use metal inhibitors. If the water is hazy, use clarifiers (organic polymers). For foaming, use reactive silicones/de-foamers. Learn their values, learn when and how much to use them. Use them if is needed. These can make life a little easier, if possible. Changing some or enough of the water can reduce many of the minerals that are causing problems.
Cyanuric Acid- Conditioner Stabilizer
This is not a basic sanitizer, but must be considered if pools are in direct sunlight, which can remove chlorine in hours. Cyanuric acid (CYA) can prevent much of the degradation of chlorine cause by the suns ultraviolet rays. If used as recommended, it can save us some (where is the chlorine?) problems.
How much CYA is enough? How much is too much? This controversy between the service pros and CYA manufactures often leaves many of us in the dark. I have preached and taught for many years that higher concentrations of CYA have no advantage, and are not cost effective. I read that we can live with a maximum of 70 ppm CYA, not above 100 pm as written in the manufacturers’ information. CYA may not lock up the chlorine at higher concentrations, but it sure slows down the killing power of chlorines, for any sanitizer to be 100% effective, it must react with pH and TA changes, move around freely, and do its job efficiently. When we surround sanitizers with anything that slows down their movements, this makes them less effective. We do not need to be rocket scientist to come to this conclusion.
I cannot recommend and overall CYA level for you, as each pool needs will vary. It depends on how much sunlight, how much water, how much traffic, the size of the filter, pump and motor, how many return lines, how far the equipment is from pool, how many hours the filter runs, cleaning procedures and much more. All of these must be considered when we add the conditioner and determine the CYA levels we will maintain. I have had services where I keep 40 ppm CYA, and other 70 ppm, and everywhere in between. Knowing each pool and all the variable mentioned, you can experiment with CYA levels and in time know how much is enough. The verdict is still out concerning the effects of CYA in determining proper alkalinity readings.
Using stabilized chlorines can often bring CYA up less time than you may think. Testing CYA often can tell you when you stop or slow down using stabilized chlorines. If above 80 ppm CYA, you can use more unstabilized chlorines, leave liquid chlorine for customers to add between calls, or change enough water to drop the CYA. How much, I cannot tell you, but 40-70 ppm CYA does the job for me. Thousands of pounds of cyanuric acid and stabilized chlorines are sold every week, if used if sunlight is a factor and in concentrations only as high as needed, this can be a big help for pros and pool owners, but if we don’t need stabilizer or stabilized chlorines, why should we make the fat cats even fatter? I cannot be convinced that higher CYA, or more is better, will make us more money or solve our problems. I use cyanuric acid and I use many stabilized tablets each year, but I do not use more than I need. I do not recommend stabilized chlorine in enclosed pools, spas, or hot tubs that are covered. This is an
added expense and we are cutting it close enough as the costs of chemicals, gas, insurance, licenses and everything we need down the line is getting out of reach. We absorb constant price increases and fat cats don’t. Save where you can, but don’t get carried away and do sloppy or unprofessional work or give poor service.
Chemicals for Balancing Water
The following recommended amounts of chemicals are added to pools, spas and hot tubs to balance pH and total alkalinity. If possible, add minimum amounts and test often; add more often. Too much is not better when these balance adjustment chemicals are used.
Is used to lower pH and TA liquid. Use only in pools with over 3,000 gallons of water. One pint per10,000 gallons. Dilute in a one-gallon jug with water- one quart acid to three quarts of water. To lower pH, pour diluted solution completely around the pool. Be careful splashing on decking, shoes, or clothing. Do not pour on steps, love seats, or near light or metal fixtures. To lower TA, pour in several areas of deep end.
Dry Acid (Sodium Bisulfate)
Is used to lower pH and TA in spas, hot tubs, and pools with less than 3,000 gallons of water, must be dissolved before adding. Never add more than 2 ½ ounces at a time for each 5,000 gallons of water. Run the filter for several hours, retest, and repeat procedure if more is needed.
Is used to raise TA in pools, spas and hot tubs. Ten ounces will raise TA approximately 10 ppm per 5,000 gallons.
Soda Ash (Sodium Carbonate)
Cyanuric Acid (Conditioner)
Is used to raise pH. Dissolve in water before adding. Follow directions on container regarding amount to be used. Never add more than two pounds per 20,000 gallons at a time. Run the system for six hours, retest, and add more if needed. Guidelines to consider when balancing pH and total alkalinity (approximate amounts): To raise pH from 6.8 to 7.2 add six ounces of Soda Ash per 5,000 gallons. To raise pH from 6.5 to 6.8 add eight ounces of Soda Ash per 5,000, dissolve before adding. To lower pH using dry acid (dissolve before adding): 8.0 down to 7.6, add four ounces per 5,000 gallons. 8.4 down to 8.0 add eight ounces dry acid per 5,000. If pH is above 8.4, use 12 ounces per 5,000 gallons of water. Run the filter for several hours, then retest, and add more if needed. Repeat procedure if needed.
For a minimum Cyanuric Acid (CYA), add 1 ½ pounds per 5,000 gallons of water. If pool, spa, or hot tub is covered or enclosed, degradation of chlorine from the sun is not a factor and stabilizer is not needed. If using stabilized chlorines, test CYA levels every 30 days. If the CYA is above 80 ppm, stop or reduce the stabilized chlorines added. Use more non-stabilized chlorines and/or change some water to reduce CYA. Recommended CYA is 40-70 ppm.
Sequestering/Chelating Specialty Additives
These are not used to balance water, but to help control or reduce the possibilities of stains from copper, iron, and other metals and scale formation. If the pool, spa, or hot tub has higher concentrations of calcium, copper, or other metals, sequestering/chelating additives hold them in suspension. Higher chlorines levels, filtration and sunlight can reduce or remove these additives; they will have to be added occasionally to frequently depending on conditions, see section on Specialty Chemicals. Remember, when you add chemicals to water, too much is not always better. There can be adverse reactions if too much is added or if some are added with others. If all else fails, read the directions on containers, some algaecides and specialty chemicals should be added with lower chlorine levels and may be more effective if added after the sun sets.
Algae and Algaecides
The three most common types of algae we will contend with are green, mustard and black algae. If correct balance ranges are maintained and concentrations of TDS, water hardness and Cyanuric Acid are where they should be, if we maintain a constant chlorine reading of 1.0 - 1.5 free and available all the time, and if the pool and filter are cleaned as needed, we should not have algae problems, sounds easy. But there are too many variables in water that either slow down or stop the killing power of chlorine. We must try a procedure that gives more constant chlorine levels. One procedure is using trichloro tablets and offline chlorine feeders, or leaving liquid for customers to add in between calls. We should also consider using some type of algaecide, at least during swimming season.
Is the easiest of the three to kill- usually by super chlorinating with liquid chlorine, cleaning the filter, brushing or vacuuming the pool, running the pump longer and employing an algaecide.
Can grow overnight in clean, clear, sparkling water. A film of alkaline or some other mineral tends to form a coating. We should steel brush this off before treatment. I have tried most types of algaecides plus chlorine enhancers to activate the chlorine, and have better luck with the old standby, copper algaecide. I use 7% copper, adding one pint to an empty gallon jug, add 7 pints of water and add one pint diluted solution to the pool every two or three weeks during the summer months. This solution should not add to much copper; if pH and TA are not allowed to drop to low and I do not over chlorinate, I do not have the copper drop out (come out of the solution into a solid and cause stains, plug the filter or cause swimmers’ hair or bathing suits turn green). Above 0.2 ppm copper, a chelating agent or metal inhibitor may occasionally be needed to hold copper in solution until some water can be changed to reduce the copper concentration.
Using copper, I find I use less chlorine and maintain a lower chlorine level (around 1.0 ppm). If I use some of the quatanarry ammonia-based algaecides, they tend to dissipate in sunlight and high chlorine levels or become trapped by the filter. I consider these more of a short-term algaecide. The copper will stay unless it drops out. It works along with the chlorine much longer, but copper can be bad news if there is too much, if chemical balances are off, or if chlorine levels are high. So, if you intend to use copper, consider all the good and not so good factors, or use less copper in conjunction with another type of algaecide if they are compatible. The black algaecide that have both copper and some type of ammonia should be considered. I stick with what works for me, but it may not do the same for the waters in your area.
Can be bad news, as it tends to thrive in cracks and porous area in plaster. It forms an oily, protective film over the roots, and even the best algaecides or chlorines available will need some help. Steel brush off the tops, then treat with additional chlorine or an algaecide. Be sure the pool and filter are clean. Algae thrives on sunlight, dirt and other contaminants. So if we can keep a constant chlorine level, occasionally add an algaecide, keep the pool clean and leave chlorine to be added between calls, we should be able to whip any type of algae problems that we find. I stress to customers that if they have black algae problems they should add the chlorine I leave and consider buying an automatic pool cleaners. If the pool has or has had advanced stages of black algae, I will not service it, as on call per week is usually not enough to control black algae. I recommend sand blasting and then chemically treating the pool, either replastering it or painting with epoxy pool paint. I have seen black algae grow through chlorinated, rubber-based pool paints. Another alternative could be fiberglass coating.
If you catch algae in the early stages, treat it correctly and maintain proper balance ranges. Keep the pool and filter clean. Be sure filter is in good condition and is adequate to filter the amount of water in the pool. Consider installing an erosion-type automatic chlorine feeder. Change some or all of the water as needed to reduce mineral build ups. Be kind to your mother, lead a good life, give it your best shot and you should be able to whip that algae problem. Remember, when using copper- based algaecides, do not overdo it. If in doubt, test the copper concentration occasionally. If it is above 0.2 ppm, use metal inhibitors until you change some or all of the water. See the section on Super chlorination for more information on when and how much if combined chlorine is above 0.3 ppm.
Langelier Saturation Index
In my service area, the water supply has moderate calcium hardness in the supply water and I am able to change water if water hardness is above 600 ppm. Therefore, I have not used or needed the Langelier, the Hamilton Theory, or any others. I know when water is corrosive or when it has scaling tendencies. So by keeping this in mind and testing water hardness occasionally, I do not need to use these complex systems. But in areas with high calcium hardness in the supply water (ours is around 250 ppm), using these formulas may be the way to go if you use all the variables and modifications needed to do this properly.
Dr. Langelier used this method many years ago to calculate a safe saturation point at which to maintain water. But this was originally for water in a closed, confined environment. Pool water is open and exposed to the air and this can be a different ball game. TDS was not included in original theories and several modifications have been added through the years to compensate for the difference in confined and closed water properties. This is too complex for me; but if I needed to use the Langelier theories, I suppose I could stagger through them. If you can follow my recommendations as to where to maintain water hardness, TA and TDS and stick with these ranges, in most instances you will not need complex formulas.
One consideration that must be acknowledged is water temperature. As temperatures change, this formula must be – re evaluated accordingly – which seems to me very time consuming. I allow a year-round average for my water and maintain ranges of pH and total alkalinity corresponding with water hardness and have been lucky so far. But in water that is heated most of the time, high in calcium content, of for maintaining commercial pools ( where health codes require saturation balances to correspond with the Langelier Index), then consider learning and using this method. But if you don’t need it, why spend the time using this method?
Different strokes for different folks. What the Ph.D. boys call the saturation point or balance, I call a buffer zone. Regardless of how we arrive at the ranges for safe, buffered water, getting there is an important part. I compared and overall balance range of my services and used average year-round temperature to compare my method and theirs, and I was right in the same area. I do not like to be technical, as I don’t have the necessary background or education, but I will give it my best shot.
Water hardness is referred to as the calcium factor (CF), total alkalinity is referred to as the alkalinity factor (AF) and temperature of water (TF), and use the pH factor of the water tested. Substituting actual numbers from my service, CF= 300 ppm; AF= 120; average TF= 66?and pH= 7.6. Add these and subtract the constant 12.1:
According to their calculations, I am as close as the original conclusions without using any modification- if within 0.3 plus or minus water was in the acceptable saturation range.
Langelier Numerical Equivalents Table and Equation Theory Chart (Temperature= TF; Total Alkalinity= AF; Calcium Hardness= CF; and pH Factor)
TA ppm......... AF
Test pH, add to TF + AF + CF, and subtract the constant 12.1
Superchlorination (Shock Treatment)
To oxide out the ammonia and nitrogen compounds and other contaminant requires adding much more chlorine than daily dosages, or adding the non-chlorine shock treatment potassium monopersulfate when combined chlorine levels are above 0.2 ppm. How much of these oxidizers are needed depends on several factors- amount of water in pool, spa or hot tub, condition of water (cloudy, green, dirty), water temperature and other variables that must be considered. There is not exact or across-the-board rule for amounts to add; although there are commonly accepted amounts that could be used as a starting point when you need to shock water. pH and total alkalinity must be in the accepted ranges before adding oxidizers. Oxidizers added to water with lower pH or TA could cause problems, as the water is already in or near the corrosive ranges and oxidizers can also be corrosive, be sure pH is up to 7.4 to 7.6 and TA is up to 100 ppm before adding additional chlorine or non-chlorine shock treatment. If pH or TA are too
low, the minerals in the water can come out of solution when superchlorinated or shocked with oxidizers. Higher pH and TA will slow down the effectiveness of the additional chlorine, but non-chlorine type oxidizers.
The recommended amount of liquid chlorine needed to superchlorinate an average, 18,000- gallon pool is from 1½ to 2 gallons of 12½% chlorine. For this same amount of water, use 1½ to 2 pounds of non-chlorine shock, or 2 to 2½ of calcium hypochlorite. In spas and hot tubs, liquid chlorine or calcium hypochlorite chlorides are not recommended, due to the high pH of both and higher calcium content of calcium hypochlorite. I recommend non-chlorine shock and/or lithium hypochlorite, not stabilized sodium dichloro. Stabilizers are not needed in spas or hot tubs because they are covered most of the time, retain heat and have very little exposure to direct sunlight. To superchlorinate with lithium, add from 1½ to 2 ounces for each 500 gallons of water. This does not need to be pre-dissolved because of the warmer water. If using non-chlorine shock, add from 1½ to 2 ounces for every 500 gallons of water.
There are no free lunches- each sanitizer or oxidizer used will have some positive and negative factors.
Using liquid chlorine where the pH is high can raise pH; you may have to compensate for this by adding acid. The same is true when you use calcium hypochlorine and lithium chlorines. The non-chlorine shock, potassium monopersulfate, will not affect pH. Positive factors: Liquid chlorine will remove chloramines and add additional amounts of chlorine to water. This chlorine residual is a fast-acting and excellent algaecide, germicide bactericide and disinfectant; it is also less expensive than some other chlorines. Negative factors: High pH, 13, bulky, short shelf life; may require 24 hours or more for chlorines to drop back down to safe swimming levels (4 ppm before swimming is recommended).
Is fast acting, granular chlorine with the same properties as listed above for liquid chlorine. Positive: Ideal in areas with lower water hardness, lower pH, and TA as a basic sanitizer for pools. Negative: high pH (11.5) and high calcium content can leave visible residue in pool. Highly combustible if water or moisture are allowed to saturate or contact dry concentrations.
Positive: fast dissolving, safer to store and transport, ideally used to activate bromine. Negative: Lower available chlorine per pound. They are more expensive than other chlorines, and they have a higher pH- 10.5
An important consideration when using any chlorine to oxidize out chloramines, is that if you don’t add enough chlorine to completely knock out these contaminants, then you can be adding more chloramines and more possible problems. Enough chlorine must be added to bring the chlorine as high as 10 ppm to completely oxidize out the chloramines.
Non-chlorine shock will oxidize shock out chloramines even if not enough is added and it will not add to the problem. Another advantage of non-chlorine shock is that swimming can be allowed shortly after adding- about one hour. One disadvantage of non-chlorine shock treatment is that it can remove the combined chlorines and also activate out the free available chlorine, leaving no sanitizer in the water. If chlorine levels are above 3 ppm, I use non-chlorine shock treatment; fill up the floater with chlorine tablets and superchlorinate as soon as possible. To be sure you added enough oxidizers tablets to do the job thoroughly, test for combined chlorines the next day. If less than 0.2 ppm combined chlorines, then you have removed some or all of the chloramines. The rule of thumb for remembering when to oxidize using chlorines or non-chlorine shock treatment is when the combined chlorines are over 0.2 ppm. Test combined chlorine the following day to determine if enough oxidizers were
Is referred to as adding enough chlorine to bring up to 10 ppm or higher; refers to adding up to 5 ppm chlorine for each ppm of ammonia. This is basically the same as superchlorination.
Acid Rain and Acid Fog
Not being a rocket scientist, I do not fully understand all that is known about these. We have both of them in my area of Southern California. From what I read, acid rain and acid fog are caused by factory and automobile emissions as well as other sources. We should have a definite lower pH and TA here after a rain, but I have never noticed any drop in these in my service route pools. Others servicing areas near here tell me the same.
In most instances, after a noticeable amount of rain, pH and TA are actually higher. I attribute this to the rain bringing in alkaline materials from the atmosphere; but I do not have a Ph. D in this phase of the pool business. Acid fog would be expected to have the same results higher pH and TA- if any change at all. At least we all agree that rain brings in enough contaminants with it to knock out or reduce the chlorine substantially; in most instances we superchlorinate after a noticeable rain. Test pH and TA after each rain; bring these up or drop them accordingly before you superchlorinate.
In years past, a home owner had two options for sanitizing their pool...Liquid chlorine or chlorine tablets. Well times have changed. Today homeowners have many more options. The term alternative sanitizer was once used almost exclusively to describe the mineral sanitizer system. Chlorine Generators and Ozonators are the latest additions to this growing category of pool products. There is considerable progress in perfecting these.
But my own personal theory is it will be some time before the bugs are out of these. I believe if these are used along with a sanitizer and not as the only source of sanitizing pools and spas, we can utilize them effectively. But for these alternative sanitizers to compensate for higher swimming loads, no swimming, variations in temperature, etc., they cannot respond fast enough, they can overcompensate or not compensate fast enough, for them to give us the safe water we need constantly.
Some are pool algaecides, but excellent at killing bacteria, or just the opposite. Some add to TDS buildups; others (ozone) do not. This should be considered if TDS buildups are a problem. All alternative sanitizers have both positive and negative aspects and all of these should be considered if you intend to try them. I will stay with what works for me; but I keep an open mind and read all the information I can find on new developments.