Water Chemistry

Suspended Solids

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.

Evaporation
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
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.

Balance Ranges
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.

Water Hardness

Total Alkalinity

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.