Cant Get Free Chlorine Up

[JoeRJGR]

Just realized I posted in the wrong spot.

Chem Geek,

Need some advice and cant post at trouble free pool because they wont give me those privileges.

I have a 35,000 gallon vinyl liner pool, which just had a new liner two years ago. When I opened it this year my PH as fine, Alk was fine, free and total Chlorine was 0, and CYA was 0.

I have once before opened the pool to find no CYA and just added some and away I went. No this year.

After adding the CYA, I added about 4 gallons of shock. Got a total Chl reading of 1.3 and a free reading of .2. Added several more gallons and ever time I did the total would increase and the free would barely move. I don't have a Taylor tester but I did order one. I felt I was in a chlorine "lock" situation and I tried to add bleach to see if I could SLAM it to the point where free would start to rise and total would start to come down. I checked with test strips and added bleach every half hour. When I reached about 38 gallons I stopped because it was getting two late in the night and I never thought I would be putting this much bleach in. That was about 4 days ago. I have left the filter running and the pool is crystal clear but I still can not get a free chl level to hold. I haven running the chlorinator on full to try and keep some Chl in the pool. I at also added some Cooper Algecide because that is only thing that has ever helped me get rid of algae, and since I cant get my Chl up I didn't want to fight that battle too.

I am prepared to stat the SLAM process again but have some questions.

1. Ben originally posted that in this situation I should turn off the chorinator so as not to "feed" the critters that were probably eating the CYA. I am holding CYA, but that may be because of the chlor tabs I'm running in my chlorinator. Should I turn the Chlorinator off?

2. Ben also stated to shock at 10 ppm at night over multiple nights. In the Slamming section of TRP, it states that you should bring the free CHL level to 12 PPM and hold it there. I have read where some people on the forum try to reach the break point testing ever 30 minutes and until they reach shock level, this is hat I tried to do earlier. Which is correct?

3. I used a 2 gallon bucket and increased adding bleach by 1/4 of a tsp till I reached strips to figure out I need to get to before FC holds. I calculated 85 ppm and 40 gallons of 8.25 % bleach. Should I add this amount all at once at night? This seems like yet a third way to try and get the FC to hold?

As I am sure you can imagine, I ma very frustrated and am thinking of at least draining half the water from the pool and starting over. Your thoughts would be greatly appreciated.

Thanks for your help.

[JoeRJGR]

Oh, and I just did an amonia test. greater than 8 ppm. Would it not be smart to turn off my chlorinators so that I am not feeding them? By the way...water is crystal clear.

[chem geek]

Did you get banned from TFP? Anyone is able to register at TFP -- did you not wait long enough for someone to let you register (they check each person to make sure they aren't a spammer)? You mention Ben, but Ben Powell is at The Pool Forum (or was), not Trouble Free Pool. So I'm confused by what you wrote.

It sounds like you had a bacterial conversion of CYA into ammonia. That takes a LOT of chlorine to get rid of that ammonia. You can get a rough estimate based on how much CYA was lost since it takes roughly 2-1/2 times that CYA loss as FC cumulatively added worst case. You can also get an ammonia test kit to see how much ammonia you have, but usually there is also partially degraded CYA that won't show up in the ammonia test. Your bucket test gives you an estimate of how much chlorine you need to add and the ammonia test you did is consistent with that (roughly 80 ppm FC or so). You can add it in 20 ppm FC increments, then measuring to see if FC is holding. Once FC holds some but still may drop, add enough to maintain 10 ppm FC if your CYA is 0. Once you are holding FC for at least a little while, you can start adding some CYA.

[JoeRJGR]

Thanks,

The CYA is stable at around 30 after I added some and because I have my chlorinator on....should I turn it off and let the chlorine levels drop before I try superchlorinating once again? Also, will 80 PPM of chlorine harm the liner, or is that not an issue since it is in the "total state"? I must have gotten the trouble free and pool form confused, sorry about that and thanks.

[chem geek]

I see you now got into TFP with this thread so it's best you get taken care of there.

The 80 ppm FC will not be a problem for the liner because you aren't raising the chlorine that high. You are adding it incrementally and cumulatively. The chlorine will get used up combining with ammonia to form monochloramine and then will oxidize the monochloramine to nitrogen gas, nitrate, and chloride.

Always add concentrated chemicals slowly over a return flow in the deep end of the pool with the pump running and right after adding the chemical brush the side and bottom of the pool where you've added the chemical to ensure thorough mixing.

I see you were able to post to TFP so you should continue the discussion over there.