Should I raise CH?

[rlsnights]

We are currently fighting black algae in our white plaster pool. :grrrr: Have been shocking it at FC 35+ along with brushing with a SS brush.

We've had some rain and it dropped our CH level a bit from 190 to 150. I'm not sure if I should increase the CH level or not. In the past on the board I was told that my CH level was fine when it was at 190 but the recommended levels for plaster pools are much higher (250 - 300). I'm assuming 150 is enough of a drop that I should raise the CH level.

Should I raise the CH to 250 or just back up to around 190?

Patricia

17,000 IG White Plaster Cart Filter Jet Vac Sweep new pumps and filter system this year; pool re-plastered 18 months ago

FC 38
CC 0
pH 7.8 (not accurate given high FC levels)
TA 130
CH 150
CYA 55

 

[JasonLion]

Yes, you probably should raise your CH level a little.

Part of what is going on is that your TA level is a bit high. When TA is high CH can be lower than when TA is at normal levels. So long as your TA is high, it is alright for your CH level to be a bit low. If you are leaving TA where it is, you should aim for a CH level of around 200. If and when you lower your TA you should being CH up to 250.