Numbers question

[chem geek]

Most likely you increased CH as your pool water evaporated and you added more water. If you test your fill water (tap water), I'll bet you'll find that it has some CH. Since whatever CH was in the pool stays in the pool after evaporation, any new water you add will increase the CH.

The only way for CH to drop is to have water physically removed from the pool as with splash-out or backwashing.

The "below minimum" for the Total Alkalinity in the report is incorrect. When using bleach, you can have a lower TA of around 80 or even lower and that will help reduce the tendency for pH to rise. Your pH is currently at 7.8 so it probably won't rise as much, but if you try to keep it at 7.5 and have the TA at 100 or more, you will probably find that it wants to rise and you need to add acid frequently.

I'm surprised they measured no CYA since if you had CYA in the past it won't go away, except from splash-out and backwashing (just like CH) though some people report CYA dropping over a winter.

Richard