Continuing to Lose Chlorine after Switching from Baquacil

[Lynne0616]

Thank you for having this forum! I have used Baquacil for 20 years and decided this year to go back to chlorine. I followed your instructions starting on August 10 (went through about 70 gallons of chlorine) and everything went smoothly….the water is crystal clear…except I can’t keep chlorine in the pool.

When I raise the FC to 15 at night, it drops to 3 in the morning. Even adding the stabilizer doesn’t help. I thought I would try four tablets of Trichlor in a floating dispenser since we only have a few weeks left of summer and the CYA won’t raise that much…but the FC still drops to zero. Added 1 gallon 10% chlorine last night and this morning was 1.5…and now zero. I have no CC but yet it smells like chlorine. How is that possible when the FC and CC are zero? We have not yet changed the sand in the filter…was going to do that today. Have also been dealing with a low pH of 7.0. Added sodium carbonate and all it did was raise the TA. Aerated pool and raised it to 7.4. Was surprised how well that worked! Pool store never mentioned that...probably because that is free!

FC 0
CC 0
pH 7.4
CYA 40
TA 190
CH 160

15,000 Gal AG Kayak Pool, 22" Waterway Sand Filter, 1.5 HP pump, pool erected 1983

[PoolDoc]

Unfortunately, if you used Baquacil for 10 years, and never drained, your pool water has a TREMENDOUS built-in chlorine demand from the deteriorated but left-over Baquacil bits.

Overnight chlorine loss will NOT be affected by stabilizer. Rather it reflects this chlorine demand. Unfortunately (again!) there are only two options: (1) drain and refill or (2) chlorinate in the evening until you have an overnight chlorine loss of less than 1 ppm.

It's not surprising the pool has a "smell like chlorine" -- that smell is almost always not the smell of chlorine (think: bleach bottle smell) but is instead the smell of chlorine + undigested goop. In your case, chlorine + PHMB (Baquacil) goop. Some 'combined chlorines' show up with the CC test, but not all do.

Regarding TA -- your pool dealers actually don't know about aeration. NONE -- and I do mean NONE -- of the regular training programs mention it. It was first published by me on PoolSolutions 10+ years ago, and you'd be amazed at all the ridicule I got. It is *still* only published on sites promoting the BBB method I developed, and there are only a couple of those, besides mine.

So while it's true that pool dealers sometimes deliberately mislead pool owners, this is not one of those cases.

[PoolDoc]

Thought of one more possible issue: you did replace your filter sand, didn't you?

If not, that could definitely be part of the problem -- PHMB leaves a LOT of residue on filter sand or cartridges.

[Lynne0616]

Thank you for your quick response! Yes, it has been drained several times in the past 20 years of using Baquacil. It was even drained 3' (leaving 1' of water) this year.

So, we will be replacing the filter sand tomorrow. Hopefully, that is the problem. It is too late in the season to drain the pool, so if need be, I will keep shocking it at night until I only lose 1ppm. What should I do during the day since even with the floating Trichlor, the FC goes down to zero?

Is my TA of 190 ok? My pH dropped down to 7.2 from 7.4...so am aerating again. It likes to stay at 7.0. :(

Next year, I would like to go with a SWC system. Any suggestions of brands? Also...do you have a favorite heater?

Thanks for your help.

[CarlD]

190 in a vinyl pool isn't really a problem, especially since your CH is low. If it was 400 or 500 you might have a problem.

I'm in my first year of an SWCG so see my comments on my results in the SWCG forum here. It won't save you money but it may save you effort.
However, I think you should clear up your remaining Bac problems first, so your FC doesn't keep dropping.

I have a FantaSea pool, first cousin to a Kayak.

http://www.poolforum.com/pf2/showthread.php?22046-Winding-Up-My-First-Season-with-an-SWCG.

[Lynne0616]

Thanks for the info!