Zero Chlorine, CYA-->Ammonia

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S

Suley

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LifeTime Supporter
May 31, 2011
246
Los Angeles, CA
Pool Size
23000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
chem geek said:
The easiest way to avoid this situation is to always maintain chlorine in the pool and never let the FC get to zero, not even for a day.

Richard
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I think I just had this situation and am handling it, thanks to this list. Mine started when i did an ascorbic acid treatment and had to leave town suddenly due to an emergency. What do you think about bringing FC to 0 when we do an ascorbic acid treatment?

Thanks!
 
Re: It Can Happen to Anyone - Zero Chlorine, CYA-->Ammonia

Your FC will get to 0 during the ascorbic acid treatment whether you let it drop or not because ascorbic acid is a reducing agent that will use up chlorine. The main reason to start with the FC as low as possible is so you don't waste a lot of ascorbic acid reacting with chlorine.

When doing an ascorbic acid treatment you usually use Polyquat 60 algaecide to help prevent algae growth and hopefully this will also reduce the likelihood of having bacteria growth as well. Did you use Polyquat as mentioned in the Ascorbic Acid Treatment article?
 
Re: It Can Happen to Anyone - Zero Chlorine, CYA-->Ammonia

Yes I did. However, as soon as the treatment was over and i was starting to balance the water, i had to leave country for a week. I asked my GF to add some more polyquat as per label directions after 5 days. She did. I returned 2 days later to see a cloudy pool and thats when all this started. I have been working on it since the past two weeks and have another thread in which this list is helping me out. i was snooping around on the website and came across this thread yesterday. Now the water is clear and starting to hold FC. Now I am trying to get past the OCLT.
 
That makes sense. Polyquat is not like chlorine. It doesn't completely stop either algae nor bacterial growth. It just slows them down enough so that, at least for algae, lower chlorine levels can be used. So given a week of time the bacteria likely grew enough to start consuming the CYA converting it into ammonia.

Sounds like you are past the worst of it. You may find that chlorine usage is still higher than normal though much slower than at first when it consumes chlorine almost immediately. This slower chlorine consumption may be from partially oxidized CYA, but as you probably saw in my summary post it took about 3 days once chlorine was holding better before the chlorine loss rate returned to normal.
 
Yay! tomorrow will be day 3!

One question though: like we know that the pH test becomes inaccurate with FC higher than 10, does the same go for the other tests (CYA, TA, CH, Etc)

Also, for people who have to hold FC more than 10 like those with high CYA, how do they perform accurate tests?
 
The only other test potentially affected by high FC is the TA test, but it doesn't become inaccurate. It just goes from blue to yellow instead of from green to red. You can add more chlorine neutralizer drops if the different colors bother you.

If you need to test for pH when the FC is high, then if there's CYA in the water and especially if you aren't shocking then the pH soon after adding the pH drops will likely be correct but will drift up over time. Another alternative is to dilute the pool water sample using distilled or deionized water (NOT tap water or bottled drinking water or filtered water). Diluting with unbuffered water won't change the pH enough to notice. You just can't use buffered water for such dilution.
 
I am assuming the first two drops which we add are the chlorine neutralizer?
OCLT passed today and I will see how the FC holds by tonight. If all goes well I'll start raising the CYA this weekend.
 
Thank you!

FC is holding now and I am raising the CYA from 30 to 40... Will be out of town for a week so i have purchased a floater and will leave the pool with trichlor pucks in it. Any idea how much of the slits to leave open in the floater? I dont think I will have enough time to play with the floater to determine.

Thanks!
 
I'd have the be open all the way and fill it with 4 pucks. For my 16,000 gallon pool, 2 pucks in a floater with the slits all the way open was only enough for around 1 ppm FC per day, but this will of course depend on the specific floater you use. 2 ppm FC per day for 7 days (so 14 ppm FC) would be 2-1/2 8-ounce 3" tablets but while the net of all the pucks may dissolve down by that much, they don't all dissolve equally so having 4 pucks probably won't be overdoing it (i.e. you'll have one or two partially dissolved pucks when you return). This assumes a typical floater that only has slits open in the bottom portion so the pucks higher up in the floater don't get much circulation so don't dissolve as quickly.
 

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