Chlorine loss & pH level

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DOMO

DOMO

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Bronze Supporter
Mar 13, 2013
379
Rowley, MA
Hi all and happy Summer (finally!). Have been having a relatively trouble free season (compared to last year with staining and high CYA), however, I have 2 issues I’d like help with (below).

By way of context, here are where some of my daily #s are:
FC & TC - see issue #1 below
TA Typically 100-110, occasionally drops to 80-90 but I promptly address with baking soda
CYA 35-40
CH 275

1. My FC is typically around 0 every day, and given my CYA level around 35-40, I end up giving a daily dose of ~72 oz of bleach to bring up to 5 target, which feels like a lot ($$) not to mention that I would expect it should level off. I have done a couple mini-SLAMs to raise it around 12ish but that has not helped to stabilize.

2. My pH seems to level off daily around 7.6-7.8 so I have to do nearly a daily dose of muriatic acid and wondering why I can’t get it to level off around 7.2 ? My pH was much more stable last year.

Thanks in advance!
 
If your FC is at zero every day then you have something in the water that needs taken care of. You don't "mini-SLAM" you SLAM Process

Your pH is rising because you are trying to keep your TA way too high for a pool chlorinated with liquid chlorine. Also 7.6-7.8 is within range, there isn't really any reason to add acid until it rises above that. Except for the SLAM that you need to do where you will want to drop the pH to 7.2 before starting.
 
Hi. Thanks for the prompt replies. Perhaps a bit of additional context might help. Last year, my CYA was sky high (80-90), so I find it funny that this year I need to add stabilizer! Also, I dealt with a terrible staining issue so I had been told to keep my pH down around 7.2 and that SLAMming would be dangerous given the multiple ascorbic acid treatments I had to do. As for TA, I had thought 100-110 was target range, but I can try maintaining around 90
 
Hi all. I've been keeping pH around 7.6-7.8. TA is finally around 85-90 daily. Have done a couple SLAMs (after dropping pH to 7.2) but FC is still at 0 each morning. Tested CYA again this morning, and it was 20 (at best), understanding how subjective this test is. Sounds like I need to get that CYA back up to 40-50 ? a. Any recommendations on what stabilizer to get from the PS? b. Is is possible to bring that CYA up quickly via using tri-chlor tabs?
 
UPDATE: Ran test @ PS, confirmed CYA was LOW! In the 10 range. Got a bottle of stabilizer. Here're my new questions:

a. trying to figure out how much to add as I want to ensure I'm not overdoing the raising of CYA (given how high it was last yr)

b. as everything else is fine (other levels are good, water is crystal clear), do I still need to do a SLAM or just bring CYA up and add bleach to target level?
 
DOMO said:
UPDATE: Ran test @ PS, confirmed CYA was LOW! In the 10 range. Got a bottle of stabilizer. Here're my new questions:

a. trying to figure out how much to add as I want to ensure I'm not overdoing the raising of CYA (given how high it was last yr)

b. as everything else is fine (other levels are good, water is crystal clear), do I still need to do a SLAM or just bring CYA up and add bleach to target level?
Click to expand...

Excessive rain water can dilute CYA quickly. Was dealing with that this spring myself.

a. At 10k gallons and a CYA around 10...to get to 30 you will need roughly 1.5 to 1.75 pounds of dry stabilizer or 25-30 oz of liquid stabilizer. Since your not 100% sure on CYA right now shoot for the low range and retest. Retest CYA after adding and recirculating for an hour or so. You may still burn FC quickly at that level, and therefore 40-50 might work better for your case...but shoot for 30 and see how it goes. Also test your FC after periodically until you have hit your desired CYA level. You dont want your FC below the minimum PPM. I try to never have my FC below the target PPM.

b. Test for combined chlorine and run an over night chlorine loss test. If CC is <1 ppm and you pass the over night chlorine loss test you should be good to go. Just working on hitting your desired CYA.
OCLT - https://www.troublefreepool.com/content/136-perform-the-overnight-fc-chlorine-loss-test-oclt
 
woodyp, I wouldn't say I trust my PS CYA reading, but then again, I don't trust the one in my tftestkit either, given how subjective it is! That said, when I did my CYA test, I filled the tube and had no more tube left to go, so it was at least 15-20 if not lower.

s_vidden, "Excessive rain water can dilute CYA quickly. Was dealing with that this spring myself" …that has not been my experience. we were dealing with very high CYA last year (90-100), and after an entire summer of excessive rain and water loss from 2 Labradors constantly pulling water out, our CYA never lowered.

I added about a 1/3 of the bottle of dry stabilizer and will test in a bit to see how CYA is looking. And I guess at the moment, I will continue adding bleach to try to maintain target FC, and not SLAM.

Thanks!
 

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DOMO,
I agree that the CYA test is probably the least accurate test in the kit. I try to mitigate that with two or 3 tests at one time and take the average. Since I only test CYA once a month, I don't use too much agent up in the kit. The CYA gets more attention during raining months or if a partial drain/fill is needed to reduce water temp.

It is a pain to adjust CYA but once your set I believe it is the easiest piece of pool chemistry to maintain. Best of luck!
 
definitely a frustrating test, and level to balance (as mentioned, last year was sky high and this yr is on the floor!). ugh.

just re-tested. FC was at 3 so added another 40 oz of bleach to try to bring it up to target. unfortunately, no change in the CYA, still filled the vile and could see the dot clearly, so added another 1/3 of the bottle of dry stabilizer (about 6 oz in volume).
 
My experience has shown that CYA needs longer than an hour to dissolve and circulate thru the system. Heck I cant even get it to dissolve that quickly in a sock. CYA was high last year more than likely do to overshooting the target. I did that once because I did not give the CYA a chance to really get worked in. Again this has been my experience but CYA (granular) takes a few days to register unlike bleach or MA.

Practice will improve ability to read the CYA tube thing. Also once I had my CYA set last year I checked monthly and never had to adjust again. Then came winter (no test of CYA required). Then this summer and sure enough CYA was around 50 if memory serves me. Now Im back at 80 with SWG going strong and no more bleach for awhile unless there is a party.

So now I treat my pool like when Im smoking meats on the smoker...low and slow.
 
UGH!! I must've misunderstood, as I thought people were telling me to re-assess CYA after an hour or so of the treatment. I REALLY hope I didn't over do it now. :brickwall::brickwall:

I think my CYA was high last year due to / before I switched from Tri Chlor to Bleach, but as I mentioned, despite all the water change out, it never dropped last year.
 
DOMO said:
UGH!! I must've misunderstood, as I thought people were telling me to re-assess CYA after an hour or so of the treatment. I REALLY hope I didn't over do it now. :brickwall::brickwall:

I think my CYA was high last year due to / before I switched from Tri Chlor to Bleach, but as I mentioned, despite all the water change out, it never dropped last year.
Click to expand...

DOMO,
I think your still OK with the amount you added. ctrav is right that it can take time for the dry stabilizer to dilute. I use the sock method as well. I would give the pool an afternoon to recirculate and test again. Perhaps an hour after full dilution is not long enough. Worst case you just add a little more chlorine for the time being to maintain target as you bring up your CYA.

Your correct that CYA would have a steady climb if using Tri Chlor.
 
hi. not sure how much stabilizer in weight. I've done those 2 doses of approximately 6-8 oz in volume.

just re-tested: FC was at 6 which is good. CYA did not appear to be much different, the dot was harder to see but still visible even with the tube filled completely.
 

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