Finding optimal pH level

[jark87]

I had reached the conclusion that adding acid weekly was just a fact of life for my pool. It’s not a huge deal, as it is the only regular maintenance I have to do, but would love to eliminate or reduce it, if possible.

I tried borates several years ago and it didn’t have any effect on my pH drift. After reading several posts recently, I wanted to revisit the pH drift topic. I read where several people mentioned finding their pool’s optimal pH and letting it stay there. I’ve never been able to keep pH from getting to 7.8 - 8.0 (maybe even higher?) if I don’t add acid regularly. I’ve tried various TA levels, ranging from 60-90, none of which made a difference. Should I expand the range? Any other suggestions? Your feedback is greatly appreciated!

Current test results:
FC - 6 (I increased SWG a bit too much. Should be back at 4.5-5 in a couple of days.)
pH - 7.4 (added 1 pt of MA yesterday. Will be back to 7.6 by tomorrow or next day.)
TA - 70
CH - 450
CYA - 65 (store was out - will increase to 70-80 prior to weekend)
salt - 3200

 

[JimMarshall]

Your CYA is already "70". Its a logarithmic scale and can't be interpreted the way you are trying to interpret it. Anywhere above the 60 line = 70. We recommend doing the test by just filling the vial to the various lines then looking - fill to 30, look, fill to 40, look, and so on.

Try letting your MA additions drive your TA lower to as low as 50 and see if that will slow youru drift down.

Do you have any spillovers or water features that run regularly?

 

[jark87]

Thanks for the CYA education. My test results were between 60 and 70, which is why I said 65. I’m bad at that test anyway, as the dot always seems to re-appear just when I thought it was gone.

As far as spillovers, yes we have a slate waterfall off the spa which probably causes more aeration than a typical spillover. It’s on the same pump as the pool, so there’s nothing I can do about it. I’ve removed the spa fountain, so at least I don’t have that any longer. I also use a Glacier chiller, which probably also adds to the aeration, but my pH drift issue existed before I had that installed.

I’ll let the TA get down to 50 and see what that does. It will take quite awhile to get there. Thanks for the help!

 

[Richard320]

See how long it takes to rise.

For instance, say you target 7.2 pH and dump in a bunch of acid. The next day it's probably already 7.4 or 7.5. Then maybe it takes three or four days to get to 7.8. And then another three or four to hit 8.0. If that's the case, it makes more sense to target 7.6 when lowering it and enjoy a week or so without adding. If you try to keep it at 7.2>7.5, you'll be dosing every other day.

In my pool, I have to add acid every time I add a couple inches of water. I can't do anything about that.

 

[Msch99]

On the CYA test, try filling to a safe line or even start at 100, then glance at it. Fill to next, glance again, continue as needed.
You can also pour it back in and do the test over, take an average if needed.

 

[JimMarshall]

Thanks for the CYA education. My test results were between 60 and 70, which is why I said 65. I’m bad at that test anyway, as the dot always seems to re-appear just when I thought it was gone.

As far as spillovers, yes we have a slate waterfall off the spa which probably causes more aeration than a typical spillover. It’s on the same pump as the pool, so there’s nothing I can do about it. I’ve removed the spa fountain, so at least I don’t have that any longer. I also use a Glacier chiller, which probably also adds to the aeration, but my pH drift issue existed before I had that installed.

I’ll let the TA get down to 50 and see what that does. It will take quite awhile to get there. Thanks for the help!

make sure when you do the test it’s sunny, you stand with the sun to Your back and the tube at waist level. Fill to one line and glance (don’t stare) then fill to the next line and glance, etc.

Chances are if you stare you’ll see the dot.

 

[jark87]

In my pool, I have to add acid every time I add a couple inches of water. I can't do anything about that.

Yes, that’s another factor I failed to mention. With the chiller, I have quite a bit of evaporation. I usually add an inch or 2 of water once a week, but if the humidity gets low or there are lots of swimmers, it can be 2x per week.

 

[mknauss]

As far as spillovers, yes we have a slate waterfall off the spa which probably causes more aeration than a typical spillover. It’s on the same pump as the pool, so there’s nothing I can do about it.

I assume you do not have automation to control the spa.

 

[jark87]

I assume you do not have automation to control the spa.

Correct. I can only control the flow to the spa. I doubt that reducing the flow would have an appreciation effect on pH.

 

[mknauss]

OK -- too bad. With automation you can schedule the spillover and drastically reduce the aeration and pH rise.