As history, I had my pool re-plastered in December 2016. For the past year or so, my PH would increase consistently .1 every day. About a month or so ago I emptied half of my pool water to reduce the Calcium hardness to 325 and the CYA to 55. To try to keep the PH more stable, I increased the Total Alkalinity from 70 to 90 by adding Baking Soda. But it made no difference. The subsequent few weeks saw the same increases in PH. Since that time the TA has settled back down to 70. It may increase to 80 when I add liquid chlorine, but will drop down when I have to add acid. Over the past two weeks, my PH has been increasing .2 or .3 every day! I don't know why. I have been using liquid chlorine because my CYA increased (last year) to 118 using tri-chlor pucks. So the liquid chlorine doesn't at the CYA but it makes my PH increase significantly when I have to add it? What is an acceptable CYA? Using the pucks would help with PH but I don't want the CYA to get too high again. Also, what is the best level for TA? Is 70 too low? That is where it wants to settle. What is the proper level of TA to help stabilize the PH? Any suggestions would be appreciated. Thanks, Mike
PH Keeps Increasing
- Thread starter mdames
- Start date
Increasing the TA will actually make the pH rise more quickly. Adding bleach should not raise the TA.
The pucks are acidic, so they would have been helping lower the pH, now with bleach your pH may rise more.
You could try lowering the TA more and that will slow the pH rise. Try 50-60ppm.
The pucks are acidic, so they would have been helping lower the pH, now with bleach your pH may rise more.
You could try lowering the TA more and that will slow the pH rise. Try 50-60ppm.
Liquid chlorine doesn't raise TA. Also your TA is the reason your pH is continuing to rise. Trichlor pucks are very acidic, this is why traditional TA recommendations are to keep it around 100. TA slows pH drop, but speeds pH rise. However, liquid chlorine is overall pH neutral. So keeping TA where it was when you were using pucks causes the pH to constantly rise. This is a normal thing most people go through when switching, part of the learning curve.
Let your TA drop to 70 or even 60 if that is where your pool wants it. Wherever your pH is more stable is the correct level.
Let your TA drop to 70 or even 60 if that is where your pool wants it. Wherever your pH is more stable is the correct level.
So are you saying that a TA of 70 is too high, and it's causing the PH to rise? The TA has been around 70, sometimes 60 for over a year. It is only recently that I raised it to 90. That only lasted two weeks. It is now 70 again. At this normalized level of 70, the PH was rising .1 per day? Is that normal? It did this for over a year. I was told that the new pool plaster was causing it. But that was 1.5 years ago now. I appreciate your reply. But the PH of the liquid chlorine I use (Leslie's) is 9. So it raises the PH every time I add chlorine. It also raises the TA, but less than the PH (and it will fall shortly after). Can I use pucks to keep the PH down, since they are acidic? What is an allowable CYA level, if I use the pucks? By the way I have been using liquid chlorine for about 8 months now, Since the CYA was 118 from the pucks. As I stated I had to drain half the pool to get the CYA to 55.
The lower the TA, the more stable the pH is kept from rising. My pool's "happy place for TA is 50.
While "out of the bottle" chlorine has a high pH, the action of oxidizing materials in the pool is actually an acidic reaction which balances out the pH. Bleach/chlorine is a pH neutral product.
You can use pucks all you want, but for a non-salt pool your CYA is already on the high side of what we recommend.
Liquid chlorine will not raise TA.
As has been pointed out, this is part of the learning curve of switching from acidic forms of chlorine to a pH neutral form of chlorine. You will notice the natural pH rise of your pool.
pH rise comes not only from chemicals, but from aeration in the pool. A waterfall, sheer decent, kids playing Marco Polo or even the returns in your pool pointing up and rippling the surface all cause teh pH to rise.
Thanks for the reply. I should add that there is virtually no use of my pool. No one uses it. There is no aeration of any kind. I do understand the concept you stated about liquid chlorine being a neutral form of it. But, if I add, say, 80 ounces of chlorine to raise my pool from 1 to 5, right after the filter has run and finished, the PH will increase from, say, 7.6 to 8.0. This is after 8 hours of filtering. Please don't be upset with me, but I don't understand how this is PH neutral. Without adding chlorine the PH would have only risen to 7.7
Yes, you will see a temporary rise, but it will be offset by chemical reactions with organics. Here is Matt's explanation form an earlier post where tehy were discussing the exact point pH rise due to liquid chlorine:
Hi Mdames
You are getting answers from some very knowledgable here but I'm going to throw in 2cents.
Take a look at pool math--link at the top of the page. At the very bottom is a calculator that will tell you the effects of adding different chemicals to your pool as long (as your pools information is filled in correctly). Playing with that some might help make things clearer.
Also, don't think of TA as a number to chase in and of itself. Think of it as a number to adjust IF your PH isn't stable. If PH keeps going up, consider lowering TA. If PH is crashing, the TA likely needs to come up. Otherwise, if PH is acting stable, ignore needing to "target" a particular TA.
You are getting answers from some very knowledgable here but I'm going to throw in 2cents.
Take a look at pool math--link at the top of the page. At the very bottom is a calculator that will tell you the effects of adding different chemicals to your pool as long (as your pools information is filled in correctly). Playing with that some might help make things clearer.
Also, don't think of TA as a number to chase in and of itself. Think of it as a number to adjust IF your PH isn't stable. If PH keeps going up, consider lowering TA. If PH is crashing, the TA likely needs to come up. Otherwise, if PH is acting stable, ignore needing to "target" a particular TA.