Boric acid question

[jamese]

I am constantly putting acid in my pool to keep the PH at 7.6 or less. Probably about an average of 12 oz. per day. My pool it 13-15,000 gallons. About every 5 or six weeks I find my Alkalinity lever has dropped from 90 to 60 ppm. The problem is putting acid in the pool to lower the PH, also lowers the Alkalinity. Likewise putting baking soda in the pool to raise the Alkalinity also raises the PH. The cat is chasing its tail. Do you recommend a dose of adding Borax will help with this problem?

 

[mknauss]

Why is your pH rising so quickly? Tell us more about your pool. Type, spa spillover or not, where in California, fill water chemistry (pH and TA), how much fill water you add, do you let your pH get to 8 before adding acid, etc.

 

[jamese]

I am constantly putting acid in my pool to keep the PH at 7.6 or less. Probably about an average of 12 oz. per day. My pool it 13-15,000 gallons. About every 5 or six weeks I find my Alkalinity lever has dropped from 90 to 60 ppm. The problem is putting acid in the pool to lower the PH, also lowers the Alkalinity. Likewise putting baking soda in the pool to raise the Alkalinity also raises the PH. The cat is chasing its tail. Do you recommend a dose of adding Borax will help with this problem?

Why is your pH rising so quickly? Tell us more about your pool. Type, spa spillover or not, where in California, fill water chemistry (pH and TA), how much fill water you add, do you let your pH get to 8 before adding acid, etc.

My pool is in-ground plaster with attached spa. Picture attached. I just checked my tap water (fill water) and found it to be 7.7 PH and 140 TA. Had my pool re-plastered 26 months ago. I was told it would require more acid until it is cured. But this is over 2 years. In fact I have drained the pool twice since the re-plaster to have plaster issues repaired. Last refill was 2 months ago in February. I live in Huntington Beach in Southern California about 1 1/2 (1.5) miles from the ocean. I have a spa connected to the pool with a spillover cut-out 12 inches wide. I don't add much water. Mostly during the warm months but pretty sure this is just from evaporation and not leakage. In the summer I may add water about every week when the level may go down 2 or 3 inches. I check my pool chemistry about every two or three days. Always at acid when the PH is over 7.6. Very rarely would I accidentally wait until the PH got to 8.0. I try to keep it between 7.4 and 7.6. For you info the pool is generally not used. My kids are grown and moved away. Nobody uses it. In fact I no longer have a heater. It is just for looks and some time consuming work. I do maintain the pool myself with no pool service.

 

[mknauss]

With evaporation, you add the high TA fill water. The continuous aeration from the spillover, raises your pH.

I would suggest you let the pH rise to 8 prior to lowering it to 7.6. You do not say what the pool water TA is right now but if over 70 or so it will need to drop some to help stabilize the pH. Realize you will always need to add acid because of the high TA fill water and aeration. You are just trying to minimize it. If there is any way to automate the spillover, that will help. It only needs to run 30 minutes or so each day to keep that water chlorinated.

As far as borates, it will not change the amount of acid you add. It will let you go more days between addition. If you would like to try it, purchase boric acid. See Poolmath for how much you will need to get to 50 ppm borates. Dudadiesel is a good supplier online. Get granular, not powder.

 

[jamese]

I have ordered borate test strips from Amazon which should arrive in a couple days. Will there be some borate in the pool water naturally? Or will it be zero? I am hoping that bringing the borate level to 50 ppm will reduce (not eliminate) the amount of acid that must be added. Also hoping it will reduce the need to add 3 or 4 lbs. baking soda every 5 or 6 weeks. My pool water TA today is at 70 ppm. My book says it should read between 80 - 100. Given my circumstances what is your recommendation for TA on an ongoing basis.

I notice you recommend letting the PH go up to 8.0 before adding acid to lower the level to 7.6. Sounds like you are saying that keeping the PH in the higher end of test reading acceptable results will help with my issue.

I can adjust the suction and pressure valves to the pool and spa near the pump in order to minimize or eliminate the spillover from spa to pool. This will help reduce the PH rise due to aeration.

 

[jamese]

Hi mknauss. You have very kindly provided me some much needed advice. Not sure whether or not you received my last post and answer to one of your questions. Could you help me this one more time?
Kindest regards, Jim

 

[mknauss]

Given my circumstances what is your recommendation for TA on an ongoing basis.

Let the TA fall to 50 ppm if necessary to reduce the pH rise. You should not be having to add baking soda and then acid.
Continuous acid addition occurs when you add high TA fill water on a regular basis due to evaporation. So your TA will not fall too low as you maintain the pH in the 7's (7.8 is fine).

If you have automation, just run the spa spillover for 20-30 minutes twice a day. Use the Spillover/Spillway function.

You can certainly use borates if you like. There are no naturally occurring borates in your water. You will use the same amount of acid. Just add it less often at much larger volumes.

 

[jamese]

I have a much better understanding now after your helpful explanations and recommendations. I will try letting my PH average about 7.8 and stop putting baking soda in the water for a while and see what happens. It sounds like a lower TA in my pool (50-60) should not be too concerning. I suspect my TA will increase in time when the chemistry settles down. Also it doesn't sound like adding Boric Acid will save any cost for chemicals. It will just reduce the frequency of adding acid. I will use the same amount of acid over time. So adding boric acid is expense I can avoid if I just check my pool chemistry often.
Thanks so much for your time and helpfulness.