The pH drifts upwards in a fairly short span of time

[TheElbow]

If you are using trichlor tablets as a chlorine source, then yes that is way too low a TA. But if you are using bleach, liquid chlorine, a SWG, or cal-hypo, then the recommended TA is 60 to 80 (or 70 to 90 depending) and your TA is too high, thus the PH drift.

Thanks very much, I wasn't aware that the Cl source affected what the TA should be. I'll try and lower it this week and see how it goes!

Love this forum!

 

[TheElbow]

pH drift.. again

I posted a while back about having to adjust my pH down more frequently than I expected ( thread here)

Mod edit: Please keep your posts about this issue in the same place so we have the history. Thanks, moderator linen


Having only a 5 months experience with my pool, I'm sorry if I'm complaining about something that isn't a real issue, but please humor me for a second.

My pH seems to drift from where I lower it (7.4-7.5) to 7.8 in about 2 days like clockwork. Given the readings below, does this seem normal? I basically have to add acid every time I add chlorine (I wait 30 mins in between the acid and cl or course!).

------------
BBB method
TA: 70-80 (pink/red appears in the test for more than 5 seconds at 70, but 80 is where it really changes over)
pH: range is 7.5 - 7.8 or 7.9 (depending how long I leave it)
CH: 250
FC: I like to keep this around 5 or 6
CYA: 40-50
DE filter with fiberclear


I decided after my last post to add borates. I used borox and in 3 sessions added enough to get the pool to 60ppm (or so I thought). The test strips seem to indicate I'm now at 80ppm, which was unexpected. I expected the borates to help keep my pH from drifting so quickly (along with following the advice from the last post about lowering my TA). But it seems like the pH drifts upward slightly faster now.

Can anyone suggest a possible solution? Am I expecting too much?

 

[linen]

Did you try lowering your TA down to 60-70 ppm like was suggested by JasonLion before adding borates?

Now that you have borates, you may have to move your TA down as far as 50 ppm.

 

[TheElbow]

Did you try lowering your TA down to 60-70 ppm like was suggested by JasonLion before adding borates?

Now that you have borates, you may have to move your TA down as far as 50 ppm.

As indicated, I dropped it to 70-80. The method for lowering TA seems to not be as exacting as adding FC, etc. Would lowering it by only 10 or 20 require dropping it below 50-60 and then raising it slightly?

 

[linen]

Would lowering it by only 10 or 20 require dropping it below 50-60 and then raising it slightly?

I am not totally understanding your question...you should be able to lower it directly down to the value you are shooting for, no reason to overshoot low.

I would lower your TA down to 50-60 ppm and see if your ph rise reduces.

 

[TheElbow]

Would lowering it by only 10 or 20 require dropping it below 50-60 and then raising it slightly?

I am not totally understanding your question...you should be able to lower it directly down to the value you are shooting for, no reason to overshoot low.

I would lower your TA down to 50-60 ppm and see if your ph rise reduces.

According to this, it seems like there's no formula for lowering TA in order to achieve a drop by Xppm. Is there another method that yields more predictable results?

 

[linen]

That is the only method, but keep in mind that TA does not move much that much with each cycle of the areation process. So you will likely do the areation cycle a number of times. I know without borates TA goes down about 10 ppm (when starting at 100 ppm) when dropping ph from 7.8 to 7.2 (from the "effects of adding chemicals" section of the poolcalcualtor.com). Having Borates in the pool does make it more difficult to move TA down.

I think you are over-thinking this, and I doubt you will swing too low with TA...but if you do a little, it is simple to use some Baking Soda to raise it back up and that will have minimal effect on ph.

 

[TheElbow]

I think you are over-thinking this

I can't tell you how often people tell me that.



I'll try and move that TA a bit more and see.



Out of curiosity, how high is too high for borates? As I said, I shot for 60ppm, and the strip looks more like 80ppm.

 

[linen]

We don't recommend raising borate levels above 80 ppm...but you should be fine there.