Testing chlorine when the pump is not running

[BigDave]

Perhaps some other localized contaminant, lotion, perfume, hair product? My point is FC is consumed and CC is created when the chlorine does it's job.

[famousdavis]

Well, I could try testing the FC/CC levels again tomorrow morning, just before the pump turns on, to see if the FC level is lower and CC level is higher than it usually is. If that's the case, I'd rule out the theory that it was a one-time, localized contaminant and I'd favor some other pool chemistry is at work when the water is still. But if the FC/CC levels are the same (or nearly so) as when I take a reading with the water moving through the pump and filter, then the theory that it just happened to be some localized occurrence would seem to be more likely.

[BigDave]

Yep, perhaps (since you're experimenting) sample and test several locations and depths.
BTW you pool is beautiful - I'm so jealous.

[famousdavis]

That's a good idea -- sampling from more than one place. I'll do that.

We're happy with how the pool project came out. It was long time wishing and planning. The upside is that I have no regrets, and I really like what we've got. It's been great during Florida's usual hot, humid summer. Before now, we used Intex Easy-set pools going back to the early 2000s, and they were fun, but as my kids grew, they outgrew those pools. I do regret we didn't build our inground pool five years ago -- that would have been the sweet spot where all my kids (4!) would have been 10 or less. But we couldn't swing it five years ago, so I'm content with what we've got and when we got it. I love it when the whole family is in the pool or spa together -- that's wonderful.