Minimizing pH rise in SWCG pools

Taken from a post written by Waterbear:

There are some adjustments that tend to make a salt pool a bit more stable in terms of water balance. The main problem with salt pools is rising pH. (This is caused by the outgassing of CO2 from the aeration of the water while the cell is on and is the primary cause of pH rise in salt pools). There are a few things you can do to minimize this.

1. Keep your CYA at the recommend MAXIMUM (usually 80 to 100 ppm, depending on manufacturer). This will translate into less cell 'on' time and therefore less outgassing of CO2.

2. Run your FC at a MINIMUM of 5% of the CYA. This will, in the vast majority of pools, insure that you won't have problems with chloramines or algae. An example, if your CYA is 80 ppm you do not want to EVER let the FC drop below 4 ppm. IF and when you ever need to shock the pool use liquid chlorine or bleach and shock to about 5 times the minimum FC level.

3. Keep TA (bicarbonate in the water) on the low side (70 ppm is a good place) because the lower the TA the slower the outgassing of CO2. The explanation is rather technical and I did explain it once in The China Shop section of the forum. (If you have a plaster pool you might need to increase your calcium hardness to maintain water balance if you lower the TA by a significant amount.)

4. Don't lower the pH below 7.6 since the lower you put the pH the faster CO2 will outgas (because the lower the pH the more you convert bicarbonate in the water into carbonic acid which is basically just CO2 dissolved in the water and the more CO2 in the water the faster it will outgas).

5. Don't worry about lowering the pH until it climbs ABOVE 7.8. You should be monitoring pH on a regular basis so this should not be an issue. Once you 'get to know your pool,' you will quickly learn that you need to add X amount of acid every Y days to maintain the pH in the desired range so it is not as difficult as it sounds!

6. Consider adding 50 ppm borate, it adds a secondary pH buffer that works together with the bicarbonate buffer to help maintain the pH in the neighborhood of 7.7 to 7.8 for an extended period of time compared to without borate in the water. You can add borate with a commercial borate product for pools (expensive) and muriatic acid (some of them are pH neutral and don't need the acid but are even more expensive) or with borax and muriatic acid or boric acid (more expensive).