can something be eating CYA??????

[carolynn]

Help! have put 10 lbs of Stabilizer into my pool and still get a zero reading. Here are my stats:
Pool 20x40, 8 ft deepend, liner

cya 0
chl 0
free Chl 0
ph 7.8
alk 120

It is clear and I have kept the chlorine at 1-3, but it rained yesterday and when I just checked it it was 0 again. i am putting the stabilizer in with a sock and each time I test it, I still get 0. How much should I need??

Also, I am using new chemicals from Taylor, so I think they should be good.
Thanks,

[CarlD]

How long have you waited after adding to test? CYA takes 48 hours to a week to fully dissolve.

[carolynn]

It has been 5 or 6 days with the last 3 lbs and the rest was 2+ weeks ago.

[waterbear]

Where did you get the CYA? Soneone on www.troublefreepool.com reported having similar problems with CYA he got from Leslies.

[carolynn]

I got most of it at Walmart, but 4 lbs of it at a pool store.
Last night I put 6 gals of bleach in which should have brought it up to 12
I forgot to test it last night, but my # now are
FC 3
CC .5
TC .5
PH 7.5
ALK 120
Cal 110
CYA 0

I am thinking I have something growing that is possibly eating the CYA when it runs out of Chlorine. I read somewhere on here that can happen over the winter. Can it be happening now too????

I am off to get more bleach and stabalizer now. How much CYA do you think I need for my pool?? I am guess ing I have 30-35,000 gals. Does that sound right??

[CarlD]

I don't usually suggest this but I think you should consider using Tri-Chlor pucks for a while. Get a couple of new floaters, and a bucket of good Tri-Chlor pucks. Avoid "Double-acting" or "Triple-Acting", and avoid ones that contain copper (HTH's double-acting).

You just want plain tri-chlor. Buy 2 or 3 boxes of 20 Mule Team Borax too.

Here's what I'm thinking:

Your CYA tests at zero and your FC see-saws. Your pH is OK and your water is clear, no obvious algae

Use the tabs at a continuous erosion rate and your FC should be very constant. Meanwhile, the Tri-Chlor will be slowly dumping CYA into your water. CYA's job is to prevent too-rapid depletion of chlorine, but you are taking care of that with the constant erosion of the tabs.

Next you'll need to watch your pH because the Tabs are VERY acid and will drive it down. That's what the Borax is for.

Floaters are cheap--adjustable ones are $10-$15.
An inline-chlorinator is far more expensive and not necessary.

For something to be "eating" your CYA, you have to let your pool turn completely into an algae pond and let it stay that way for a month or two--YECH!!! Either you don't yet have enough for a reading (I THINK you need 15 lbs for your pool--but don't take that as gospel), or you are testing incorrectly, or you didn't add as much as you thought, or you've replaced more water than you realize.

Now, instead, of this, you can keep adding CYA and using bleach to chlorinate. Absolutely nothing wrong with that.

I don't object to Tri-Chlor tablets IF THEY ARE USED APPROPRIATELY! This would certainly be an appropriate use of them.

Good luck!

[waterbear]

I am guestimating that your pool is about 33k gallons from the dimensions and assuming a 3 ft shallow end and a rectangular pool. 10 lbs of CYA should certainly get you to about 40 ppm. Try an experiment to make sure your testing reagents are good. Take a sample of pool water and put it in the CYA dispensing vial to the water line and add 1 particle of CYA to it. Add the CYA reagent to the reagent line and shake for about 2 minutes and then let it sit for 5. The sample should turn very cloudy and when you put it into the CYA view tube it should read very high. If it does not then you probably have bad CYA reagent or the CYA is not CYA!

Also, have you cleaned or backwashed your filter after adding the CYA? If you did then it is possible that you washed it out of the pool before it all had a chance to dissolve.