Sky-high PH

[Ps6fsu]

This is a 1 yr old plaster pool and first time opening after being covered all winter. Full disclosure - I started another thread HERE in regards to the calcium crystals I had on the plaster. Got those off and removed but now battling chemistry probs. I assume my PH climbed all winter since it is a newer plaster pool. I was adding about a half gallon of muriatic acid every 10-14 days during the swim season to keep the PH in check. Upon opening, my PH was so high that it could not be read with the Taylor kit. It was beyond 8.4 so not sure what actual reading was to start. I posted the timeline below but to summarize, I have now gone through a 10 lb bucket of dry acid and 3 gallons of 31.45% muriatic acid and I still am not able to get an accurate PH reading. Pool math tells me that all of that acid combined should reduce my PH by 4.9 and TA by 82. It has always been very accurate. My TA has gone from 180 down to 100 so that is consistent with pool math as well. Is it possible my PH was really that high (13.5+)? Or do I have something else going on?

Sunday - Water At Opening:
FC = 0
PH = Well above 8.4
TA = 180
CH = 250
CYA = 90
SALT = 2600 ppm
Temp = 52
CSI = 1.23

Monday AM: Raised water level with tap water (PH of 7.8, TA of 70) and added 3 lbs of 73% Cal hypo shock, 6 lbs of dry acid (2 doses 4 hrs apart), and 40 lbs of salt

Monday PM:
FC = 9
PH = Well above 8.4
TA = 170
CH = 275
CYA = 70
SALT = 2800 ppm
Temp = 55
CSI = 1.27
Action: Added 4 lbs dry acid

Tuesday AM:
FC = 1
PH = Above 8.4
TA = 160
CH = 300
CYA = 70
SALT = 2800 ppm
Temp = 57
CSI = 1.33
Action: Added 2 gallons of muriatic acid, vacuumed, backwashed, turned SWG up to 80% from 30%

Tuesday PM:
FC = 1
PH = Above 8.4
Action: Added 1 gallon of muriatic acid, 2 chlorine pucks to skimmer (not sure my SWG is working)

Wednesday AM:
FC = 2.5
PH = Above 8.4
TA = 100
CH = 300
CYA = 70
SALT = 2800 ppm
Temp = 60
CSI = 0.67
Action: Confirmed high PH with test strip. Added 1 gallon of muriatic acid

 

[ajw22]

PoolMath pH calculations for acid additions are not accurate with large quantities of acid.

You should never add acid to reduce pH by more then 0.3 in one dose.

Keep on adding acid at 0.3 pH reductions and test your pH and TA between doses. You will see your pH come into range.

I saw this after one winter when it took me 5 gallons of 31% MA before my pH came into range.

 

[Flying Tivo]

Please do not use Dry Acid, it will hurt your SWG life span. Only use MA.

 

[ajw22]

Also, I would get your FC up to 5 or more using liquid chlorine ASAP. You don;t want to complicate your problems with algae.

Do you see the color or the pH test changing as you have been adding acid?

 

[Ps6fsu]

Thanks guys.

@Flying Tivo - I have never used dry acid before but my local pool store was out of muriatic acid and wasn't sure when it would be back in. I since found another store that has it so I stocked up.
@ajw22 - Thanks for the tips on dosing. I will be a bit more conservative going forward. How long would you say to wait between 0.3 reductions? In regards to getting my FC up - im going to the store after im done work today to get some liquid chlorine until I can figure out why my SWG is not producing any. For PH, I did notice the red getting a tad lighter after each dose. The test this morning gave me some hope bc it looked like it would be 8.6ish if the value was there.

FYI - I actually just went out and tested again to see how the gallon I dumped in this morning affected the results. The PH is now 7.2 and TA is 80. I know 7.2 is a tad on the low side but Im sure it will creep up in the next week or so as it always does.

 

[Newdude]

but my local pool store was out of muriatic acid and wasn't sure when it would be back in. I since found another store that has it so I stocked up.

HD/Lowes/Ace have it in the paint aisle year round. I imagine any ShermanWilliams, Benjamin Moore (etc) would as well.

 

[ajw22]

FYI - I actually just went out and tested again to see how the gallon I dumped in this morning affected the results. The PH is now 7.2 and TA is 80. I know 7.2 is a tad on the low side but Im sure it will creep up in the next week or so as it always does.

Thats why I was cautioning not to do too much acid in one dose. Once the pH comes into range you can overshoot on the low side.

You caught it in time. With TA of 80 your pH of 7.2 is fine.

Move on and get your FC up now.

 

[Ps6fsu]

HD/Lowes/Ace have it in the paint aisle year round. I imagine any ShermanWilliams, Benjamin Moore (etc) would as well.

Yeah, i found some at Ace. HD and Lowes had it but it was the lower concentration stuff.