California Closing - Low TA

[scdaren]

I just did the full line of tests as I usually do this time of year to "close" my pool. I say that in quotes, because I don't actually close since it doesn't get cold enough here in California, it's my end-of-season routine. I'm seeing TA of 50, and I've never seen it get that low before. My pH usually rises all the time, but I haven't added acid in quite some time and am sitting at 7.9. My sense is that I'm good to leave it as is, as long as the pool seems happy, and it does. Any reason to bring the TA up?

This are my results before adding anything:

FC 2.5
TC 0
pH 7.9
TA 50
CH 550
CYA 30
Temp 64
CSI 0.07

My plan is just to run about ten 3" trichlor tabs two at a time in a floater over the month or so to bring the CYA back up to 50, and that should keep my pH and FC pretty well in hand, then go back to liquid chlorine, which I add very little of in the winter months. Water is getting cold enough now there isn't much concern of algae, which I've never had an issue with.

 

[kul]

I have a similar TA situation with same size pool. I don’t see any issues with leaving it as is if your CSI is in range and your ph is reasonable.

 

[mknauss]

My plan is just to run about ten 3" trichlor tabs two at a time in a floater over the month or so

Only issue is the above. If you are not adding any fill water with TA, the acid in the trichlor will reduce the TA further.

 

[mgtfp]

As Marty said, those pucks will reduce your TA. Per 10ppm of FC that you add via trichlor, CYA will rise by about 6ppm, and TA will get reduced by about 7ppm (once the added FC has been used up).

Adding 10 3'' pucks will add 80oz of trichlor to your 15k gal pool, which will add about 37ppm of FC and 22 ppm of CYA. TA will get reduced by about 26ppm. With no Alkalinity added e.g. by fill water, this could end up in a pH crash.

 

[scdaren]

Only issue is the above. If you are not adding any fill water with TA, the acid in the trichlor will reduce the TA further.

As Marty said, those pucks will reduce your TA. Per 10ppm of FC that you add via trichlor, CYA will rise by about 6ppm, and TA will get reduced by about 7ppm (once the added FC has been used up).

Adding 10 3'' pucks will add 80oz of trichlor to your 15k gal pool, which will add about 37ppm of FC and 22 ppm of CYA. TA will get reduced by about 26ppm. With no Alkalinity added e.g. by fill water, this could end up in a pH crash.

Thanks for the feedback -- I will keep an eye on this. This pool is four and a half years old, and I've dealt with constantly rising pH since it was built. I'm normally adding muriatic all summer long to keep my pH and CSI down with the higher temps, and let it rise up on its own during the winter when the cooler temps keep the CSI down. I probably go through 8 to 10 gallons of pool-strength muriatic over the course of a summer. I'll honestly be really surprised if my pH drops noticeably from these tabs -- this won't be the first time I've used them in this way, and have never seen that happen before. But I'll check pH and TA again in a week or so, I've got a bucket of sodium bicarb here if it looks like the TA is dropping much more than it has. I would love to figure out how to get my rising pH under control, and am wondering if lower TA is the answer to that. Increasing TA has never helped.

 

[mgtfp]

Sounds like you know what you're doing. All good as long as you keep an eye on things, which you seem to be doing.

Just want to make sure that newbies reading this thread understand the consequences of using tabs, and that they need to be used with care as an add-on to TFPC. Keeping TA down while chlorinating with bleach is quite straight forward, but with trichlor (and dichlor) some care has to be taken. Plus keeping and eye on CYA.

 

[duraleigh]

I am fairly sure your TA at 50 ppm has slowed your pH rise.

Fifteen years ago, TFP accepted the pool industry standard Range of 80 - 120 ppm.

We now know that a TA of around 50-80 tends to stabilize pH better so that is our suggestion. You are on the right track.

 

[jesse-99]

I am fairly sure your TA at 50 ppm has slowed your pH rise.

Fifteen years ago, TFP accepted the pool industry standard Range of 80 - 120 ppm.

We now know that a TA of around 50-80 tends to stabilize pH better so that is our suggestion. You are on the right track.

Agreed. My pH rises constantly due to lots of aeration in my pool, but keeping that TA lower around 60-80 helps me slow the rise of pH overall as compared to when its around 100-120. I sure get tired of adding MA every other day.... ugh.