pH always high and white flakes

[ctmd]

Hello, first time poster here. Please go easy on me. I'm having a very hard time getting my pH below 8. Adding about 32-40 oz of muriatic acid a week from the hardware store. I've read that since our plaster is about a year old that may be contributing.

Complicating this is the fact I added NoPhos from Leslie's about 6 weeks ago (took over pool care 8 weeks ago) when our level was 600. Since then we've had white flakes in the pool (improving with time). I've cleaned our filters twice (4 weeks apart)and run the Sigma vacuum every 3rd day or so in the spa and pool. The scale in our negative edge spa on horizontal surfaces (glass tile) keeps coming back rapidly after I use a red rubbery calcium brush. I've run in spa mode to get more water through the filters to no avail. Flakes look like a fine particulate dust, some bigger. Water is crystal clear otherwise.

Any advice appreciated. Thanks.

Recent test results
PH = 8.2
FC = 4.8
CC = 5.0
CH = 360
TA = 110
CYA = 30

 

[ctmd]

More info is that we have 2 bubblers on a tanning ledge that are always on.

 

[Texas Splash]

Welcome to TFP! A few comments for you:
- Double check the CC result. Perhaps a type of some sort? Maybe you meant 0.5?
- Bubbles add aeration which increases pH. Is there any way to turn them off when the pool is not in use?
- Your TA can afford to come down some more which should help slow the rise of pH. When the pH hits 8.0-8.2, use enough muriatic acid per PoolMath to lower the pH to 7.2. Then let the pH rise on it's own and repeat. Each time you do this it should lower the TA a little. Once the TA gets down to about 60-70 the pH increase should slow down.
- Your CYA is low for a salt pool. We recommend a min of 70 to protect the chlorine generated by the SWG.

Do these things and it should help with the scale. Bookmark our Pool Care Basics page for lots of great info.

 

[Dirk]

When I had high TA, I built bubblers that I could attach to my returns in order to raise pH, so I could then lower it with acid, which lowers the TA, just as Pat has described. Point being, you're running your water features like a giant pH-increasing bubble machine. The constant running of the spillover and the bubblers, along with high TA and newish plaster, is causing your pH to rise. Either you get used to using muriatic acid, or you install an automatic acid dosing system, or you run your bubblers and spillover only while enjoying the pool, or some combination of those.

I have high TA fill water, and plaster that drinks acid for breakfast, lunch and dinner. I installed an IntellipH acid dosing system and let the machine do the work. The IntellipH only works when its companion IntelliChlor is present, so it wouldn't work for you, but there are other acid dosing systems available, if that's something you'd consider.

Right now, your CSI is about +0.7 (positive). You should try to keep it negative, ideally around -0.3 (negative) to help avoid calcium build up on your SWG's plates. If yours is like mine, your SWG reverses its polarity every so often, to dislodge the calcium build up, which gets spit out as flakes into the pool through the returns. If your flakes appear primarily piled up under the returns, that might be what you're seeing. Running your CSI negative should help eliminate them, and that means stabilizing your pH around 7.2 (with a TA of 110). If you can get your TA down to 60, then your pH could be around 7.5 to maintain a CSI of about -2.4. Fool around with your Pool Math calculators to see how CH, water temp, TA and pH affect your CSI. But I can tell you from my own experience, maintaining a stable pH and a negative CSI with high TA fill water means pouring acid multiple times a week (and that's with NO bubblers and NO spillover). With my IntellipH, which dispenses acid every hour, it's me filling the IpH tank every few months...