No Chlorine?

[MartyW]

I had already put 5 gallons in around 9:30 pm before I saw your last post. At 10:30 pm I read FC @ 17ppm and CC @ 4ppm. At 6:30 am I read FC @ 1ppm and CC @ 1ppm. This evening was FC @ 0 and CC @ 0.5ppm. I'm baffled! Thanks for your help. Marty

[aylad]

Those test results say that there is something in the water that is consuming your chlorine, so the next step is to take it to shock level (chlorine 20 ppm) and hold it there until you can go overnight, testing just like you did, but not losing more than 1 ppm of chlorine in that time.

If you used trichlor pucks last year, what was your CYA when you closed? I'm betting it was high, and the fact that you had none on opening means it degraded over the winter. One of the possible byproducts that it sometimes will degrade to is ammonia, which creates a very high chlorine demand, but one that must be overcome with lots of chlorine before you'll be able to hold a chlorine level overnight. We've seen a lot of that happening this year, unfortunately.

Janet

[Watermom]

Jan,
I started replying and was pretty much writing the same thing you wrote above but deleted mine. The puzzling thing about this one is that even if she did have CYA bio-degradation over the winter, why doesn't she have a high CC reading? I've asked Ben to take a look at this thread.

[PoolDoc]

The puzzling thing about this one is that even if she did have CYA bio-degradation over the winter, why doesn't she have a high CC reading?

She *has* had transient high CC levels. The thing you have to remember is that breakpoint chlorination -- so long taught in the pool industry -- actually WORKS, when the chloramines come from simple ammonia chlorine mixes. So, 'shocking' to eliminate chloramines can potentially do just that.

[MartyW]

I don't know if this has any bearing, but I never opened the pool last year. We were out of town part of the summer and also had some remodeling done. I don't know what the cya was 2 years ago. If what you are saying is continue to shock, how much chlorine would I need? The water looks great, clear and sparkling - just no chlorine. By the way, I'm a guy. Thanks, Marty

[aylad]

With a CYA of 60, shock level is 20 ppm, and you need to sustain that as consistently as possible until you can go overnight without losing more than 1 ppm of chlorine. I don't know how much total that will be, but

[MartyW]

I've looked at the best guess chart. I'm still at a loss as to how much shock I need to put in to reach the desired level.

Marty

[aylad]

With a CYA of 60, shock level is 20 ppm, and you need to sustain that as consistently as possible until you can go overnight without losing more than 1 ppm of chlorine. I don't know how much total that will be, but

Boy, that was helpful, huh Internet went out in the middle of editing that post. Thanks, Watermom, for finishing it for me!

[aylad]

I had already put 5 gallons in around 9:30 pm before I saw your last post. At 10:30 pm I read FC @ 17ppm and CC @ 4ppm. At 6:30 am I read FC @ 1ppm and CC @ 1ppm. This evening was FC @ 0 and CC @ 0.5ppm.

With a FC of 17, and a CC almost 25% of that, something's eating it up. May or may not be ammonia, but either way the pool still needs shocking.

Edit: Pooldoc's post button works faster than mine tonight!