Constantly reducing PH, is this normal?

[MalcolmV8]

I've had the pool / house for 5 years now and while most everything chugs along fine I find I have to bring the PH down every week, actually it's every few days but I settle for once a week because sodium bisulphate is expensive. My PH is always pegged at max on test kit which is 8.2 when I check it.

I was adding muratic acid for the longest time and then realized it was lowering my TA so I switched to sodium bisulphate. It seems to leave TA alone but weekly or bi-weekly 1lb seems excessive to me. Maybe it's normal?

Sometimes I ignore it for a month but then I start seeing signs of light yellow algae on the steps which I assume is from overly high PH now allowing the chlorine to do its thing.

My water readings are usually around this
CYA 80 ~ 100
Chlorine 8 PPM (anywhere from 6 to 10, I try and target 7 ~ 8)
TA 80 (I've dumped lbs of arm and hammer pure baking soda to raise TA but it seems to be very temporary and comes back. Always seems to find its way to 70 ~ 90)
Ca hardness 275 (275 ~ 300)
Salt 3200 (goes down and up over the months of course with usage and adding)

Located in FL tampa bay area if it matters. You guys have to drop PH down as much?

 

[ajw22]

Rising pH is normal in many pools.

High pH does not stop chlorine from doing its thing. You have other issues causing the algae.

Do you have any water features or spa spillover running creating aeration?

I suggest you go back to using Muriatic Acid...

Acid - Further Reading

www.troublefreepool.com

Dry acid can be used to lower pH and TA. However dry acid contains sulfates which will accumulate in the water. Dry acid should not be used in plaster pools or pools with a SWG.

Dry acid is often sold as “pH Minus.”

Dry acid is sodium bisulfate. After dissociation of the acid salt, it leaves behind the sulfate ion.

Problems sulfates can cause include:

• Sulfates can damage concrete & plaster
• Excess sulfates in water increases the likelihood of corrosion on metal parts
• Excess sulfates in splash out water leads to degradation of any concrete surfaces
• Sulfates degrade the coatings on SWG plates
• At high enough concentrations, sulfates can react with calcium to form spindly, needle-like crystals of calcium sulfate (gypsum)
• While sulfates in vinyl pools is typically not as problematic as in plaster pools, scaling of gypsum crystals can increase the risk of liner puncture.

Sulfates can only be removed by draining water.

Pentair specifically says on page 9 in the IntelliChlor SWG Manual - CAUTION: The use of dry acid (sodium bisulfate) to adjust pool pH is discouraged especially in arid regions where pool water is subject to excessive evaporation and is not commonly diluted with fresh water. Dry acid can cause a buildup of by-products that can damage your chlorinator cell.

 

[jark87]

My pH also rises every couple of days during the summer. I chalk it up to the SWCG, as it has a higher run rate than during the winter. My chiller also adds aeration, but I had pH rise before adding it. As far as TA goes, try lowering it to 60. That won’t eliminate your pH rise, but might slow it down. I’ve only used muratic acid, so I can’t comment on what you’re using. As noted above, your algae problem isn’t caused by the pH level. Your CYA may also be a tad high. I also maintain FC in the 8-10 range and CYA at 80, but err on the low side with CYA since the test is so subjective. My CYA may be closer to 70.

 

[MalcolmV8]

Rising pH is normal in many pools.

High pH does not stop chlorine from doing its thing. You have other issues causing the algae.

Do you have any water features or spa spillover running creating aeration?

I suggest you go back to using Muriatic Acid...

I may have misspoken on the PH to algae relationship. I used to keep track of this in a spreadsheet in the early years and looking back I believe I had very low CYA at the time that was my likely culprit.

No water features or spill overs. I assume you're asking due to aeration of the water. I have noticed my pool cleaner seems to suck air in the water lines at times and causes little bubbles to blow out the return lines in the pool. It's very minimal but does catch my attention from time to time and I've wondered if that's enough aeration to affect my TA?

Very interesting info on the sodium bisulphate. I never realized that. I can switch back to muratic acid.

 

[MalcolmV8]

My pH also rises every couple of days during the summer. I chalk it up to the SWCG, as it has a higher run rate than during the winter. My chiller also adds aeration, but I had pH rise before adding it. As far as TA goes, try lowering it to 60. That won’t eliminate your pH rise, but might slow it down. I’ve only used muratic acid, so I can’t comment on what you’re using. As noted above, your algae problem isn’t caused by the pH level. Your CYA may also be a tad high. I also maintain FC in the 8-10 range and CYA at 80, but err on the low side with CYA since the test is so subjective. My CYA may be closer to 70.

Agreed on the pH affect on chlorine. I misspoke on that and responded above.

Thanks for letting me know yours also rises that quickly. I agree it is indeed the SWG as I switched for bottled chlorine manual dosing for a couple weeks and noticed the problem went away.
I always thought TA buffered pH and the higher the TA the better at buffering but you are saying just the opposite and I should let it come down. Did you not mean to raise it?

 

[Spencer2024]

You'll also get some of those tiny bubbles coming out of the return when your SWCG is working. And yes, higher pH comes with SWCG. I just dose 8-16 ounces a few times a week. I'm pretty new at managing this myself but I have come to understand that the pH is probably a bigger battle during swim season.

 

[reggiehammond]

SWCG usage does not raise pH, that's a myth. Chlorine pucks are highly acidic, driving down pH and TA. When people switch to a SWCG, they now no longer have the pucks pushing down on pH.

Fill water, especially from wells or municipally-supplied wells, are typically higher in TA than your pool. Raising TA causes pH rise, which requires adjustment.

 

[jark87]

I always thought TA buffered pH and the higher the TA the better at buffering but you are saying just the opposite and I should let it come down. Did you not mean to raise it?

No, lower TA will help slow the pH rise. As far as SWCG and pH rise goes, this is from TFP Expert Chem Geek:

SWCG pools do tend to rise in pH over time, but it's not due from the higher pH of chlorine addition per se, but rather other processes we are still sorting out such as increased aeration of the water which has carbon dioxide outgas faster (which can be reduced by having a lower TA level) and with undissolved chlorine gas outgassing (so it doesn't stick around to lower the pH from dissolving in water nor from oxidizing something).

All I know is that my pH rise can be easily tracked with increased SWCG production. When I’ve had SWCG failure and had to maintain FC with LC, I didn’t have pH rise. I just accept that I have to add acid at least once a week during the summer and about once a month during the winter. Our pool is open year-round and always has some level of SWCG production, except when water temp gets below 50°, which is rare and only for short periods.

 

[MalcolmV8]

I appreciate the feedback and info guys. Sounds like my weekly dosing for rising pH is perfectly normal.