Chlorine magically disappears!!!!

[scootchu]

I have a friend who is a 2nd year pool owner. It's an above ground 24' 52" high round pool. He opened the pool, vacuumed, ran his robot, dumped in 3 gallons of 12% and no change.

I went over with my Taylor kit suspecting his CYA was high, but I got a 30-40ppm reading. His pH was a little low and I advised him to add some Borax and more chlorine since my kit had shown nothing.

He added 6 gallons and the next day, no change in the milky green color. He took a sample to the pool store and they said his levels were good aside from No Chlorine.

He bought 5 more 3 gallon containers (or are they 2 gallon?) He put them in last night and woke up to the same colored pool as he has. He has test strips and they read No Chlorine. Could they be bleaching out?

In any case his Alk, pH, CYA all seem to be okay.

Now he replaced his sand in his filter right after opening the pool. I am starting to suspect he may have done something to the filter that has rendered is useless in filtering. I told him that new sand isn't as efficient as older sand, but he is new to this.

So what could be eating his chlorine. Is his CYA too low to keep the chlorine in the pool? I wouldn't think so and he added the 4-5 containers of liquid chlorine in the evening.

My pool went from brown to clear in 2 days. His seems to be stuck.

[madwil]

I calculate the pool about 13k gallons, so 3 gallons of 12% would give 30 or so chlorine- very easy to bleach out some tests! try a cheap OTO test, or your own FAS-DPD test... the OTO test will turn brown, I think at high FC levels...

We really need complete tests to advise- he could have extreme ammonia build up if a lot of CYA was used before, or other issues...

[BigDave]

Perhaps your friend has algae? All the chlorine can be quickly consumed killing algae.
How about testing every hour after bleach goes in - see if you can catch some before it's consumed. If that pool is 15,000 gallons he 3 gallons of 12% should raise the FC well past 20.

[scootchu]

No doubt there is algae, but would it consume that much chlorine? I will take my test kit over to his pool.
Every experience I have had is that chlorine in that amount would knock it out fairly quick unless the CYA was way too high. I measured between 30-40ppm with my test.
Very strange.

[TonyPH12345]

ABSOLUTELY.

I had a fairly nasty algae outbreak early this spring. It took tens of gallons of bleach and probably 8 pounds of CalHypo to eradicate it.

[scootchu]

Well I went over there and he has 4.5ppm of FC. I told him to get some Cal-Hypo at the store. He told me he closed the pool green, which I din't know. He said he was yo-yo-ing all last summer, green, cloudy, clear.
His Alkalinity is 80 and his pH dropped a bit again. I told him to get some more Borax, which I swear by. If he dumps enough in to hit the magic ppm number, he'll be in better shape anyway.

[aylad]

Unless his pH is extremely low, he'd be better off to fix one thing at a time--and he really needs to concentrate on the chlorine demand first. If he needs to add Borax to get the pH above 7.0 then by all means go ahead and add it--but I wouldn't worry about trying to raise the borate level, at least not until he gets the chlorine demand taken care of. If he closed the pool green, there's a really good chance that some or all of his CYA was converted to ammonia during the winter, and that can create a HUGE chlorine demand (and sometimes for a really long time)that must be overcome before he's going to be able to get a clear pool. He's going to need to get the chlorine up to shock level (see the "best guess chart in my sig for proper levels, based on his current CYA number) and keep it there until he's able to hold chlorine in the pool. That can take lots and lots of chlorine and time, but he'll need to accomplish it to have any good swim time this summer.

Janet