Where did my CYA go?

[tlwilson]

Can CYA reagent go bad? I have been running 50 all season and last tested about 3 or 4 weeks ago. Today I tested CYA and the dot never disappeared. I had a mishap today that turned out OK and I was lucky. I needed to add a couple of inches of water so I turned on the hose an hour before I needed to leave for work. I forgot to turn it off and went to work. I came home at lunch, which I never do, and found the water within an inch of overflowing. All day would have made a big mess! Anyway, I dumped a bunch of water by running the filter to waste, reducing about 5 inches of water to the proper level. I know that couldn't wipe out my CYA. The only explanation I have is that the reagent went bad. Any other ideas?

 

[jblizzle]

Well, sorry to say that the CYA reagent is about the least likely to actually go bad, so something else is going on.

Have you had a lot of rain in the last month? Pumped off a lot of water? Are you sure the water was not going out an overflow today and overfilling?

 

[pwrstrk]

I know last month we had anywhere from 9-12 inches of rain. I had to add alittle CYA.


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[tlwilson]

We've had more rain this spring than usual, but we're usually in a drought, so it seems like a lot. About a month ago I drained about 2 inches of water, but that's about it. I don't think I have an overflow. When I tested FC right after draining today, it was 6.5, which wasn't much off of what I would have expected. Seems so odd.

 

[tlwilson]

I bought new CYA reagent today and the result is still the same. Can still see the dot, but a little cloudy. A sock of stabilizer is hanging in the pool now.

 

[pwrstrk]

Good job. Wait about a week and retest.


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[tlwilson]

I added CYA and raised it to 35. That was one month ago. I tested a couple of times on different days and it was 35. Today it is back down to 20. I'm sure I am doing the test right. We get little rain and I add water about once a week, so I'm not draining. I haven't even had to backwash much, maybe twice in the last month. Pool is clean, clear and sparkly.
FC 6.0
pH 7.6
Alk 70
Any ideas on what could be going on?

 

[Donldson]

How much water do you add weekly? It might be worth trying a bucket test to rule out the possibility of a leak.

 

[linen]

Do you have an autofill?

 

[tlwilson]

I don't have an auto-fill. I add about an inch of water a week when we don't have any rain. I thought that seemed like a reasonable amount to lose through evaporation. What is the bucket test?

 

[Donldson]

It does seem reasonable, but it won't hurt to rule out a leak. You take a 5 gallon bucket (with straight sides), fill it with water and put it on a step in your pool. Use a sharpie to mark the water levels on the bucket, one for the level inside, one for the level outside. Let it sit for a while and compare the water levels. If the level in the pool goes down faster than in the bucket that will indicate a leak. If they lose their water evenly then you can rule out a leak.