pH staying at 7,2

[carlscan26]

I can't seem to keep my PH at 7.6; it always goes down to 7.2

Numbers as of this evening:
CYA: 60
FC: 3.5 (a bit low I know, I ran out of CL and haven't had a chance to get more - it was at 7 on Saturday)
CC: 0
PH: 7.4 - 7.2
TA: 80
CH: 130

This past weekend I raised by PH using borax to get it to 7.6 on Friday and again on Sunday (it dropped back to 7.2 on Sat). This also raised TA from 60 to 70 and on Sunday I raised TA further to 80. Today it measured 7.4 - 7.2; not quite either color just right in between.

My wife and daughter are complaining that the pool water is stinging their eyes at 7.2. The FC was at 7 that day but that's in the range for a CYA of 60 (rec FC 5-9).

Should I raise my TA more?

 

[chem geek]

Yes, you can raise your TA more which will tend to make the pH rise more, but what are you adding to the pool that is lowering the pH? Are you using Trichlor pucks/tabs? Are you using Dichlor or MPS? If you are just using bleach or chlorinating liquid with The Liquidator, then I don't understand what is making your pH drop.

Also, I doubt that the pH of 7.2 is causing stinging eyes since that's not very low. That's more likely to be caused by Combined Chlorine (CC) so you should check for that. Or if they are keeping their eyes open in the water for long periods of time then that can cause pressure which is less likely to occur in pools with higher salt levels. Nevertheless, raise the pH and see if your daughter notices any difference.

 

[carlscan26]

I'm only using liquid CL via the LQ and manually added as needed. So I'm equally confused why it keeps drifting down. I haven't had to fill it often since I have it covered with a solar blanket...after the recent rains we've had it hasn't gone lower than 7.2 and I've always adjusted back to 7.4 or 7.6 only to see it go down again. It's been about the last month and a half that I've been having trouble keeping it at 7.4. Maybe pollens or dust right now? The cover is kind of dirty/dusty.

I measured the water before we went swimming and the FC was 7 and the CC was 0 - that was about 2 hours before we got in. 3 hours after we swam I retested and FC was 6 and CC was still 0 so I don't think we had any CC while we were swimming...the eyes open makes sense with my daughter - she was diving for rings (she's a fish! )

Per the pool calc to raise my PH from 7.2 to 7.6 I should be seeing TA rise by about 8 too, but I've never seen it move that much; it started at 60 back in January and moved to 70 after several attempts at raising the PH. Last weekend I dosed it with baking soda to bump it to 80. How high would you recommend I take the TA to next? Increments of 10?

Thanks Chem!

 

[chem geek]

One other thing to note is that you should measure the pH at roughly the same FC level, preferably when the FC is lower (if it varies -- with the LQ it probably doesn't vary too much, but may be lowest just before the pump comes back on for the day).

As for TA, yes I'd just go up in 10 ppm increments and wait some days and see if it makes a difference. No reason to overshoot this. I'm still puzzled, though.

 

[carlscan26]

You and me both. I'll try for 10 today.

 

[frustratedpoolmom]

Keeping the solar cover on frequently will cause your ph to drop as you describe. I experience this in my pool - and its covered with the blanket when it's not used.

 

[dmanb2b]

Keeping the solar cover on frequently will cause your ph to drop as you describe. I experience this in my pool - and its covered with the blanket when it's not used.

Same here. Not sure why, but even if we are not using the pool in the middle of the day, we uncover it for at least an hour to "air out"...Likely would be fixed if I just bumped TA up a bit, but then my PH rises in the hot months when we use the pool the most

 

[carlscan26]

Interesting...

 

[JamesW]

Keeping the pool covered will reduce the outgassing of carbon dioxide, which will reduce pH rise. Uncovering the pool allows carbon dioxide to off gas, which will raise the pH. Warmer water and aeration from increase usage will also increase carbon dioxide off gassing. I'm not sure why there would be a pH drop from using a cover.