Adjusting CH in and SWG pool

[vetman85]

I've noted the recommended CH for an SWG pool is higher than a non-SWG pool. First, why the difference? Also, my pool is fairly consistent at CH between 275-300. I keep the other readings in line with the TFP recommendations (typically only needing to adjust pH)...so wondering if it's necessary to raise the CH slightly. Thanks.

 

[needsajet]

The higher CH recommendation compensates for the lower TA recommendation. We recommend lower TA for SWG pools to slow the faster pH rise typical of SWG pools. By using a bit more calcium, the calcite saturation index (CSI) will be closer to zero than at the lower CH recommendation, which helps protect the plaster. After you enter your results in PoolMath, you can see the CSI result at the bottom. There's every chance you'll be fine at 300 and keep in mind that your CH is likely to rise a bit due to evaporation and refilling with water that has calcium. For plaster pools, a slightly negative CSI is a good place, so -0.2 to -0.1 is a good range to shoot for.

 

[pooldv]

Especially with Dallas water which is prone to scale which makes it especially I portent to keep CSI between -0.3 and 0.