Evaporation is the culprit here. You add water to your pool and it turns to vapor and goes away. The minerals and residual chemicals remain behind. You add more water, the evaporation removes it and the concentration becomes greater. Unfortunately, Chlorine (our favorite poolside HALOGEN), usually comes in gaseous forms, bound with solids. Usually, these are cyanuric acid, calcium, lithium, or sodium and when you add the chlorine to your pool, you are also adding a certain amount of one of these substances! After a while, a build-up of these materials can develop, and some of these can cause problems in balancing your pool's chemistry.

Calcium is listed first because of it is the most abused of the four and causes more than a good share of problems. A certain amount of calcium is important to maintain in the pool to eliminate some of the corrosive nature of water by keeping a BALANCE between the water and the structure of the pool itself. Low calcium causes etching of the plaster, gelcoat, acrylic, and vinyl surfaces. High calcium on the other hand, as caused by STRESSED WATER, can develop scaling on the tiles, in the pipes, in the equipment, cloudiness that will not clear, deposits of brown to gray mounds on the plaster, can turn sand filters into a piece of junk with a giant chunk of sandstone in the middle. Moderation is the main key here and knowing the calcium content of the base water supply is important because draining is the only remedy and on extremely high cases sometimes multiple drainings are needed because scaling has become so advanced that when fresh water is added, the calcium deposits in the plumbing sometimes go back into solution (to some degree) and give readings that are off the scale with fresh water!

Cyanuric acid (STABILIZER) is the second most often reason for stressed water. Most chlorine tablets contain this binding agent and are continuously adding it to the pool while keeping the residual chlorine level correct. Fortunately, just about the worst thing that happens from too much stabilizer is that the efficiency of the chlorine is slowed to the point that your 75 degree pool can turn green (almost overnight!) when it has a residual chlorine level of 6.0 p.p.m! This doesn't happen overnight either, because it can take months (up to years in some cases) for the stabilizer to build that high, and can usually be avoided with regular professional testing (SEE ALSO "IDEAL WATER BALANCE PARAMETERS"). There are two possible cures for excess cyanuric acid, one is removal by chemical means ( a process that should be done when the weather is being nice and no real chance of algae contamination. The initial step is to neutralize the chlorine and sometimes people tend to overdo it with the chemicals. It can sometimes take days, or even weeks, to rebalance the pool after a real mistake!) and the other is by physically removing (draining) the stressed water and replacing it with fresh (unstabilized) water. Although, the draining programs are considered usually the best for most pools, many pools' requirements are such that chemical removal is actually a far safer way to go. Seek Professional help.

Sodium Chloride in the pool water is fine if the pool has a chlorine generator installed in the system, but if it is being added into the chemistry as BLEACH, a corrosive agent (salt) is being needlessly added to a system that can do well without it. The chlorine content is low enough to make it TOO EXPENSIVE to use (especially after replacing equipment and equipment and ...) on any pool without a chlorine generator (which uses salt to manufacture the chlorine with) that happens to be well used and regularly exposed to algae. Many liquid chlorines are in reality merely glorified bleach and have almost the same composition!

Lithium in the water doesn't seem to do anything other than calm down unruly neighbors. Lithium baths are supposed to be very popular in some parts of the world and at the time of this writing, no stains are attributed to it, no deposits, no scaling, no interference of the chemical balance whatsoever. One of the only drawbacks to this marvelous chemical is the cost. Usually as expensive as stabilized chlorine, it takes two and a half times as much to do the same job because it is only 35 % active! No problem on a spa or hot tub, but on a 20,000 - 40,000 gallon pool that can be dramatic. However, if the tub is covered, as many hot tubs are, Lithium based Chlorine can be a perfect solution, and it works well with OZONE systems!