TOTAL ALKALINITY (TA) refers to the amount of alkaline materials in the pool water. These alkaline materials act as buffering agents and help control Ph. If the TA is too high, changing the Ph is difficult because the water resists Ph changes. High TA can also cause cloudy water, mineral stains, eye irritation, chlorine inefficiency, and calcium scaling. Water with low TA is sensitive to Ph changes, and will bounce” from high to low Ph as you try to adjust Ph. Water with low TA also tends to be corrosive, irritating to eyes, etching in concrete and plaster, corrosion of metal fittings, and can be colored (usually light green).
The suggested TA for Diamond Brite or marcite finished pools is 100-150 ppm. If you pool is fiberglass, vinyl-lined or painted, maintain TA between 125 and 175 ppm. Since TA has an effect on Ph, it is normally adjusted before any Ph adjustment is made. If the TA is below 100 ppm and Ph is above 7.2 you can raise the TA by adding “BICARB.”, If the Ph is below 7.2 add “Soda Ash” to raise Ph to proper level first. When increasing TA, the water may become temporarily cloudy for a few hours, but will clear. If the water has a TA above 175 ppm, it may be common for the area and no adjustment may be necessary. However if adjustment is needed Muratic Acid is the chemical that is used to lower TA. If the pool has a very high TA it may take many treatments to lower. When acid is added to pool water with a High TA the TA level is reduced. Also, there will be a small drop in Ph. Since a high level of TA still remains, the Ph will bounce back up to its original level. Because of this treatments for TA should be spaced at least 12-24 hours apart to assure proper test results