Upwards pH Drift Without Significant Aeration

[ThatOneExcelGuy]

Current measures:
FC/TC: 2
pH: 8.0
TA: 80
CA: 300
TDS: 1200
(Calculated LSI: 0.24)

Every week I have the same balancing issue. I go to test pool water and it has invariably drifted back up to somewhere around 8.0 (SD 0.2) (as measured by phenol red, meter occasionally reads higher but may need recalibration).I end up adding ~1.5 pints of muriatic acid and retesting the next day. The pH will have returned to a somewhat tepid 7.5 with TA remaining somewhere around 80. Of course, this constant addition eventually lowers TA and I have to acidulate the water so that it may tolerate dosages of sodium bicarbonate without becoming excessively alkaline. I had considered that the production of carbonic acid from waterfall may have been the cause, but there is no way for me to shut it of without hampering circulation.

In short: My pool consistently runs with high pH and low-normal TA. I am hoping to find some variable I’m not controlling for so I can reduce the amount of HCl introduced to the system.

Thanks in advance.

 

[mknauss]

Welcome to the forum.
EDIT -- What level of TA are you allowing your water to get to?

 

[proavia]

I see you are sharing your PoolMath logs to your forum account.
Log all your results in PoolMath and save them there.

In PoolMath, turn on tracking for:
Combined Chlorine
Water Temperature
CSI (we don't use LSI as it's an old standard for boilers - CSI is a better indicator for pools)

What model number Taylor test kit do you have? Add it to your signature.

Let your TA settle to 60-70. This will slow your pH rise.
With a lower TA, you may find your pH likes to settle around 7.8 or so. As long as the CSI is in the range 0.30 to -0.30 (negative 0.30) you are good.

TDS doesn't really matter - it includes calcium, CYA, salt and other dissolved solids.
We test for calcium, CYA and salt (especially those with a SWG) already. The other dissolved solids usually aren't a big deal for pools.

How are you chlorinating?
What is your CYA?

 

[MITBeta]

Lowering pH with acid and followed by bumping up TA with baking soda (which often masquerades as mysterious, expensive "pH Up") is classic, pool store, hamster wheel stuff.

Also, your FC is likely too lower depending on what your CYA is. See FC/CYA Levels.