Puzzled about no FC

[LearningCurve]

Hi ALL,
Started lurking last year to resolve common problems. Now I have one I can't figure out so here is my first post.

I have a three year old 16X32 IG w/vinyl liner, about 25,000 gallons. My cover was ripped during a late winter storm so we opened to some nasty water. I had my original installer open and clean the pool because I wanted him to inspect for liner damage etc.

The water cleared up pretty good in about 5 days. I was testing with an OTO kit that only goes up to 3 ppm on TC. The water was testing off the scale for TC and PH was about 7.6. After another week the OTO tests were consistent with the first and the water looked great! I took a sample to my dealer for verification. Their tests show:

FC .2
PH 8
TA 180
Ca 190
CYA 30
Copper .01
Iron .1

I thought surely there was a mistake so the next day I had them test again with similar results. I picked up some test strips and they tested similar to the dealer.

So here is what I did. I started aerating, I added muratic acid over a two day period to bring the PH down to 7.2. I then added 4lb CYA trying to get it up to 55 and added 5 gal of 6% bleach to shock it. The dealer is closed so I can only check with my OTO and strips for now. I checked after 30 minutes. There is no FC according to the strips. It shows:

FC 0
PH 7.4
ALK 170
CYA 50-60

24 hours later tested the same.
Since the OTO is off the chart for TC, I diluted 1/3 pool water to 2/3 tap water (tested TC free). The OTO still tested above 3 ppm but the strips still show no FC.

Is it possible I actually have over 10ppm CC ?
The water looks and smells great.
My auto TriChlor Chlorinater is wide open, plus a few in the skimmer.
I have Ben’s new kit on order.

Any Ideas?
THANKS!

[duraleigh]

My first reaction would be to blame the strips...however, the pool store agrees with the strips so I'm cautious not to jump to conclusions.

My bet is your OTO is right. It's normally very dependable if somewhat subjective.

If at all possible, I'd try another set of results from a different pool store just for some reassurance.

Ben's kit will solve the issue. Hope you get it soon.

[tundraSQ]

I am kind of reaching here...so you might do a search....I believe I have read that with some tests, it is possible to have SO much FC as to register as ZERO....anyone else read that here?

[waterbear]

some strips will bleach out with high chlorine....depends on the reagent that they use.l

[LearningCurve]

some strips will bleach out with high chlorine....depends on the reagent that they use.l

I was attempting to rule this out by diluting the sample with tap water. I started 1/3 pool to 2/3 tap water, and the strip tested no FC. I actually did it again 1/4 to 3/4 and still got none.

[waterbear]

When you closed the pool was your CYA level higher than the 30 ppm you tested now? If so it is possible that some of your CYA biodegraded. This would cause a huge chlorine demand since the bacteria will excrete ammonia compounds and urea.

[LearningCurve]

When you closed the pool was your CYA level higher than the 30 ppm you tested now? If so it is possible that some of your CYA biodegraded. This would cause a huge chlorine demand since the bacteria will excrete ammonia compounds and urea.

I know that the CYA was arount 40 when the pool was closed last year. The bill from my dealer has 4# of "conditioner" So I assume that they put CYA in also. So my best guess is that there wasn't much left at open.

If this is the case, how much chlorine would a guy need to put in to overcome, and still not damage the liner?

THANKS!

[aylad]

Check the Best Guess chart sticky note at the top of the chlorine forum...

Janet

[LearningCurve]

Check the Best Guess chart sticky note at the top of the chlorine forum...

Janet

I don't think you understood my question.
I realize that the best guess sticky has 15ppm as a shock level.
I have already put enough chlorine in that should have taken it beyond 15ppm.

This would cause a huge chlorine demand since the bacteria will excrete ammonia compounds and urea.

How much should this take to overcome this ammonia compounds and urea ?
At this point I am assuming I have a WHOLE BUNCH of CC.
IS CC bad for the vinyl liner?

I appreciate the help!

[waterbear]

Just keep your total chlorine levels at 12-15 ppm and keep hitting it with chlorine morning, noon, and night until the FC starts to hold! It might take a LOT of bleach but it will eventually hold. If you let your chlorine levels yo-yo up and down it will take longer so just keep testing and adding bleach to keep the level at about 12-15 ppm and you should be fine.

For more info read the posts by PoolDoc (Ben) in this thresd
http://www.poolforum.com/pf2/showthread.php?t=401