Strange test results -- very high combined chlorine (CC)

[BigDave]

If you'd like to work up an estimate of how much chlorine will be required to clean up your pool, perhaps you could try: Bucket testing for chlorine demand.

Be calm. Frustration and impatience very often drive us to look for a "Magic Fix". "Magic" is never what it appears to be and in a pool usually makes the mess worse and the cleanup longer and more expensive.

[Watermom]

How are you testing for CC? Your numbers are bizarre. How does the water look?

[Themadczar]

Water is clear with a very light green tinge. Sides are not slippery, and brush is never green after brushing the pool. Normal taylor 2006 test process... 10ml pool water. Scoop of powder (turns red). Count drops of 0871 until it stays clear. Each drop is .5ppm fc. Add 5 drops of 0003 (turns red again). Count drops of 0871 until it turns clear again. Each drop is .5 ppm cc.
I know the numbers are bizarre. That's why i keep posting/updating here.
I intend to add 4 gal of bleach tonight unless someone suggests differently...

[PoolDoc]

Sorry I hadn't picked up on this sooner.

You are almost certainly experiencing the well-established problem of cyanuric acid conversion to ammonia or urea by bacteria. This results in the HUGE chlorine demand, and high CC levels, you are seeing. There are only two solutions: (a) drain and refill - NOT safe on vinyl IG pools, OR (b) chlorinate until the demand is gone.

You can use the bucket test BigDave described to answer, approximately, the question, "How much more chlorine will it take?". Or you can just chlorinate till it's done.

For a variety of reasons, you are probably better off doing this at a higher than normal pH, but you can't go very high with Alk and CH over 300 ppm. So, I'd recommend using borax to push the pH to ~7.6, and holding there till you get the situation under control.

Do NOT swim while you are doing this. High chlorine is rarely a problem for people, but high chloramine levels are something different.

Adding CYA will slow the process at this point. My recommendation would be to
1. Use borax to raise the pH to 7.6, and hold it there.
2. Dose each evening with 4 gallons of household bleach UNLESS the TOTAL chlorine (FC + CC) is greater than 20 ppm. Skip doses when TC levels are above 20 ppm.
3. Use the bucket test if you want to find out how much longer you have to go.

Sorry about this. We had many, many cases last year, with the super-warm spring of 2012. This year, with a record cold spring, there have been very few cases.

[Leehicks79]

Scoop of powder (turns red). Count drops of 0871 until it stays ...

Shouldn't it be TWO scoops of powder?

[BigDave]

if it turns pink, one is enough.

[Themadczar]

Ok, thanks. At least i know what I'm dealing with. However I have added 5lbs of dichlor in the last few days... My cya should be around 23 (I'll test tonight unless it takes longer to fully dissolve and I would just be wasting reagents). Does that change your recommended evening dose of chlorine, PoolDoc?

[PoolDoc]

Not really.

CYA may slow the reaction of chlorine with ammonia, but not by much.