Still Learning.....Got Another Question

[Z7What]

I had been keeping my TA at 90-110 based off Pool Math. Keeping it at this level i found that my pH wouldn't hold steady. I was told that the 100 target for TA is just a default in Pool Math and isn't whats recommended for my pool. I was having to always add acid to lower it down from 7.6-8.0. I learned that the TA at the levels i was keeping it at was the cause of the pH always wanting to climb. I later found out from Pool School that I should be keeping it at around a 70. So with advice from the great members on here I was told to add enough acid to lower my pH to a 7.2. I did this, the next day the TA was a 90(was 110) and pH was a 7.3ish. The following day my TA was still a 90 and pH was perfect at 7.5.

With that being said if my pH still continues to climb should I do another acid drop to 7.2 to "burn" off some more TA? But its my pH stays at a 7.5 that would mean my pool likes to have its TA at a 90 right, and dropping it to 70 shouldn't be needed?

Wayne

 

[tim5055]

TA is a moderator for pH shift, so if I understand your question - yes, if your pH is stable leave the TA wherever it is.

 

[Bama Rambler]

That is correct. It's all about balance. Don't worry about adjusting the TA specifically as long as it's within reason. Adjust the pH as needed and let the TA settle where it wants to.

 

[Z7What]

Thanks Fellas!

Wayne

 

[Z7What]

One more question.

I got my TA to 70 and pH held perfect at 7.5 for 2 weeks. We just got back from vacation yesterday and I did a full round of tests and noticed TA was now at a 80 and pH was a 7.6 so it looks like it may start slowly climbing again. What happens first, does TA move and then it causes pH to climb or pH move and it causes TA to rise?

Not sure how much rain we got when I was gone to possibly explain the pH level but I cant say for sure. I know aeration of the water causes pH to climb but what causes TA to rise?

Wayne

 

[gregsfc]

One more question.

I got my TA to 70 and pH held perfect at 7.5 for 2 weeks. We just got back from vacation yesterday and I did a full round of tests and noticed TA was now at a 80 and pH was a 7.6 so it looks like it may start slowly climbing again. What happens first, does TA move and then it causes pH to climb or pH move and it causes TA to rise?

Not sure how much rain we got when I was gone to possibly explain the pH level but I cant say for sure. I know aeration of the water causes pH to climb but what causes TA to rise?

Wayne

Not answering the question; I'm waiting for an expert reply too, because everything I've read states you've got to add buffer to raise TA; but one possibility of course could be just different test results from a pool with equal TA levels just showing up 10 points different on two different test occasions.

But with regards to the TA dilemma in general and constant PH rises, I just finished with a multi-page thread where I had the same issue and was guided to a solution by Chem Geek where my TA is now kept at 43 to stabilize the PH in my pool; I was adding muriatic acid 4-5 times per week; every time my PH hit 7.9, and about every two weeks, I was raising my TA with baking soda. Every time I tried to do larger adjustments, even though it would reduce PH further down the scale, it would just climb back up to 7.9 in about the same amount of time as if I had adjusted it only slightly down, but when I'd double the dose of acid, I'd have to almost immediately add soda. Like you, I did not at first catch on to the TFP recommended level of TA between 70-90 and was going by the "traditional pool" level of 80-120, so I was targeting in the middle around 100. In the end, my TA ended up @ 43 before my PH would stabilize and not rise. Chem Geek calculated my carbonate alkalinity (or something like that), which shows how resistant my pool is to a PH crash at that low TA level. Turns out that as long as I don't do something crazy with an acidic-based chemical, I'll be okay and managing the pool the TFP way is much easier now that I'm usually only adding bleach.

 

[Bama Rambler]

My first thought is that it's a test issue. Since the test is only +/-10ppm it could have been a test anomaly.

Rising TA is normally caused by either adding something that raises TA or by high TA fill water.

 

[gregsfc]

I've noticed only TA drops; never had TA come up on it's on with only a drifting upward PH problem. Back when I was getting the constant, rising PH; which had been for a season and a half, I would drop it a couple of points at a time with 7 oz's of MA in my 7500 gallon pool. Once per week, I'd test TA. It always worked it's way down when continually adding acid. For me, it was about as the pool math shows that it will using MA. I'd leave TA alone until it took 5 drops to clear the vial before I'd add enough BS to bring it back to 80. And the cycle would continue. What stopped the insanity for me was, while working with experts on here with my PH creep thread, and after testing the TA with it going clear after only 4 drops; I simply left the TA alone to see what would happen. Turned out, nothing happened, the PH quit climbing. Chem Geek got involved; did the calculations; problem solved.

So maybe what tim5055 first replied is the key. If you add just enough acid to get PH to stay in range; and then you just let TA stay where it is once you've accomplished some PH stability; it'll probably save this endless cycle that I went through. One has to be aware though of adding chemicals with acid after reaching this stability, because then, the PH and TA could drop below that natural state. I'm referring to things like CYA, dichlor, trichlor. I would think, but don't know, if you purposely or accidentally changed your CYA (since it's sort of a semi-permanent level and it is an acid) that could change the PH/TA dynamics of the pool. Calcium--maybe--works into it as well. Chem geek needed to know my CYA, PH, CH, and TA to do the calculations.

But all I'm doing right now is adding bleach daily, and the rain does not lower my PH or TA where I live, so I feel like I'm pretty safe @ TA 40ish, because the only time my pool has ever dropped PH other than on purpose, was back before TFP. I was using trichlor exclusively then, so that sort of makes some sense. If I needed to throw in dichlor or trichlor for some crazy reason, I might test TA and add some buffer just to be safe. Or if I wanted to raise CYA; I'd probably start over and test and adjust my PH for a while like before to get a new stability. I'm no chemistry guru, but I'd think, with a CYA 10-15 points higher, one may require a higher TA to maintain PH, but I'm just sort of rambling at this point...

 

[chem geek]

TA can rise from evaporation and refill since fill water has TA. It can also rise from plaster curing if calcium hydroxide or calcium carbonate get into the water, but that would be accompanied by a strong pH rise. Most likely in this case is either test error or a small TA rise that was on the border between drops (i.e. not a full 10 ppm).

 

[Z7What]

Checked pH again yesterday and it was still at a 7.6 maybe a slight chance of 7.5. So it just may be a sampling threshold that appears to be larger than it actually is. Thanks guys, you always get me straight. So far I'm loving this TFPC method, never have I been so confident about my pool!

Wayne