Not sure what to do, need advice

[Tex599]

Water is clear and clean, but noticed this year my FC levels drop overnight. Yesterday morning my results where:

FC 3
CC 1.5
PH 7.8
TA 110
CH 290
CYA 80

Added 6oz. acid and 1 gallon 10% bleach that morning

Tested last night

FC 6.5
CC 0
PH 7.4
TA 110
CH 290
CYA 80

This morning, after pump had been running for 30 minutes

FC 3
CC 0.5
PH 7.4
TA 110
CH 290
CYA 80, maybe 90 (it's hard to tell)

It looks like I need to maintain FC of 7ppm, but I can't get it to stay there. Any advice, thanks!

 

[Jezza]

I'd say you could have an underlying algae issue brewing, Did you do the morning test before the sun hit the pool?

 

[pooldv]

I agree, a little something in the water. A surprise from a bird or something, who knows. Minimum FC means that it should never go below 7, ever. Once below 7 the pool is not sanitary and algae can grow. I'd raise FC up to 15-20 for a few days and give some extra brushing and recheck the Overnight Chlorine Loss Test in a couple of days.

 

[Richard320]

 

[Tex599]

Thanks! Yes, this morning test was before the sun was out. It's a cloudy day today here. Can you still swim with the FC at 15-20?

 

[Richard320]

Thanks! Yes, this morning test was before the sun was out. It's a cloudy day today here. Can you still swim with the FC at 15-20?

With 80 CYA, sure. That's way below shock level.

 

[Tex599]

Perfect, thanks!