We are in our 5th season with our pool. In a moment of weakness I allowed myself to be talked into Baquacil last year. We had algea problems in the first year so I decided to go back to chlorine this year. The folks at my pool store were not happy with my decision and weren't very helpful about converting. Thanks to all of you I finally figured out how to go about it!
The conversion seems to be complete. The pool store test said there was no Baquacil left in the water. We changed the sand in the filter. But I still cannot maintain FC over time. The level is high in the early am but by noon it is 0. The water is hazy. You can easily see the bottom but it isn't crystal clear either.

My current numbers are:
FC: 0
CC: .4
pH: 7.5
TA: 196
CYA: 75
Total hardness: 275

They also tested for phosphates which were negligible but they still had me add a bottle of PhosFree. Then they had me put in 6 bags of shock. The next morning the FC was 10 at 7 am. By 11:30 am it was 0. I took another sample in and they ran a chlorine demand test. They said I needed to add 5 bags of TurboShock. I didn't have TurboShock on hand so added 8 bags of hth Super shock n swim (52% hypochorite). Again the FC level was 10 in the early am but 0 by noon. Last night I put in 10 bags of Super shock n swim. This morning the FC level was somewhere beyond 10 (my test doesn't register that high) at 8:30 and 0 by 12:30.

From some of the posts I've read it sounds like I should be shocking more often. I thought I had to wait until evening.

My kids are frustrated because they can't swim. My husband is frustrated at the $$$ we've been throwing in the pool. I have no confidence in the folks at my pool store whom I've trusted the last 4 years so I'm just plain frustrated. Please help!

Your description sounds an awful lot like low CYA. Are you confident in your test result and does that match with the CYA you have added, either directly or with dichlor shock?

What you're describing is caused from CYA being zero. If you're holding FC overnight but losing it very quickly in the sun, your CYA (stabilizer) is most likely zero. Have you added any CYA, trichor, Dichlor, Etc?

Welcome to TFP!

I can think of a couple of possibilities. Everyone else is favoring low CYA, which is my first guess as well, but there are some other possibilities.

First, it doesn't really sound like you finished the baqua conversion. Did you follow the entire procedure spelled out in Pool School here?

Second, how did you get that CYA test result? Was that a pool store test result? Have you intentionally added any CYA? If CYA is actually near zero, that could explain everything.

Third, you might have algae, but that seems like the least likely possibility. If CYA really is 75 and you have algae, you haven't added nearly enough chlorine quickly enough to have killed the algae off.

It would be very interesting to do an overnight FC loss test. You are clearly able to maintain some chlorine overnight. If you don't lose any then the problem is a low CYA level. If you do lose chlorine, then it is either algae or an incomplete baqua conversion.

Do you have a test kit of your own? If so, what kind?

I suspected the stabilizer level too but the numbers seem okay. I added stabilizer at the end of May and again 1-1/2 weeks ago after losing a lot of water vacuuming the pool to waste. I also am using Bioguard Pool Pods in my skimmer.

My numbers are from the pool store. My test kit is from WalMart.

I thought I had followed all the Baqua conversion steps to the end. We are thinking of replacing all the hoses in case there is Baqua hiding in there.

Those pool pods have trichlor and will add CYA to your pool.

Question, why did you go through the process you learned here, then go right to being pool stored?

You really need a good test kit with a CYA test you can trust!

You latest comments point at algae as most likely. I still suggest doing an overnight FC loss test to start with.