What chlorine level to shock -- now that half my CYA is gone

[JimK]

Tonight's test showed I lost 6ppm FC during the day (SWCG is off). It was partly cloudy today. I'll let the pump run overnight with the filter on to see how much I lose overnight.

If there is a loss, I think we can safely say something in the filter is consuming CL since last night with the pump off there was no loss. If the loss isn't that much I think I'll just let CL do it's job over time rather than tearing down the filter (or maybe shock it one more time). Tomorrow morning's test should tell us more.

[JimK]

This morning's CL test showed I only lost .5ppm FC (CC is still 0) overnight with the filter running. So I'm guessing that whatever was consuming CL overnight was knocked out by that last shock.

The good news is I can stop shocking and don't have to tear down the filter. The bad news is we don't know if the overnight loss was caused by gunk in the filter, in the pool, or both.

So once FC levels drop to normal, 5-6ppm, I can work on getting the SWCG set properly and get to a normal maintenance routine (which usually doesn't involve much with our pool). FC was 12.5ppm this morning so I expect by this evening it will be close to the normal maintenance level.