CYA dropped, Trichlor okay to bring it back up?

Michael57

Member
Mar 30, 2020
11
Sacramento, CA
My CYA started at 50/60, but over the past couple of months it seemed to have dropped to 40, and then today it tested at 20. I'm quite surprised as we haven't lost that much water out of the pool.

Since I've been using liquid chlorine, is it okay to use some Trichlor that a previous owner left? I placed it in a floater, but do I need to run the pump non-stop until it's dissolved? How long does that usually take to dissolve?

My pH was about 7.7 and I've been lowering it with muriatic acid but if Trichlor will lower it that works. My FC was about 4 this morning...
 

Jeff J.

Well-known member
Aug 6, 2019
223
Staten Island NY
My CYA started at 50/60, but over the past couple of months it seemed to have dropped to 40, and then today it tested at 20. I'm quite surprised as we haven't lost that much water out of the pool.

Since I've been using liquid chlorine, is it okay to use some Trichlor that a previous owner left? I placed it in a floater, but do I need to run the pump non-stop until it's dissolved? How long does that usually take to dissolve?

My pH was about 7.7 and I've been lowering it with muriatic acid but if Trichlor will lower it that works. My FC was about 4 this morning...
If those results are accurate, I don't see any reason not to. It will raise your CYA and lower your PH, although your PH is fine. It will also lower your TA. Keep an eye on all those numbers, and stop using it if they get out of whack.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,315
Laughlin, NV
If your CYA is at 20, you should use dry stabilizer/conditioner to raise it back to 50 ppm quickly. Pucks will be slow and the potential for FC to drop below the minimum is high.
Always test CYA monthly during the summer. I lose 10-15 ppm CYA per month. Elevated water temperatures accelerate its degradation.
 
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Jeff J.

Well-known member
Aug 6, 2019
223
Staten Island NY
Thanks for the help, I just tested again and I think it's actually 30... That makes sense on the elevated water temperatures. I'll pickup some dry stabilizer...
The CYA test is very tricky. Make sure you have your back to the sun, hold it at waist level, and just glance (don't stare) to see if you see the dot.
 

Oly

Gold Supporter
Jun 28, 2017
1,676
Fresno, CA
Monitor your daily FC loss, and if not significantly higher then there is no immediate need to raise CYA from 30 to 40. Calculate how many 8oz tabs of trichlor you need to add 10 ppm and be sure to monitor your pH. No need to fully dissolve the tabs in one float and no problem pulling out the floater for several days and dropping it back in. Plan to add your normal liquid additions each day to keep FC in the zone or a few ppm above and test to confirm. Easy really.