Lowering TA, Raising CH and PH

[seano]

Aloha. I have a 28000 Gallon in ground plaster and tile pool. Pentair Pumps and Sand Filters , Chlorine feeder towers using 3" Trichlor pucks. My test kit is a Taylor Complete High Test Kit.
Last year I had very high CYA. I replaced about 80% of the water. CYA is currently at 60 ppm. Not too bad! I now have a very high TA 250 ppm going on with a very low CH 100 ppm. The PH ppm was 7.6 and my FC was 7 ppm prior to adjusting the TA. I added 4 gallons of Muratic Acid, about half of what I expect to need to get to the goal. I let it sit overnight. I retested in the morning and got 175 ppm TA. Going down! I turned the pool feeder ports pointing up to naturally aerate the water for the past 24 hrs to try to bring up the PH which has dropped to the low 6's after adding the acid. I wanted to give the aeration a change so no adjustment was made to the PH for now. Its now about 48 hours now. I want to add more Muratic Acid to get the TA to its optimum of around 80-100 ppm. However the PH did not come up with aeration. I want to bring up the PH but don't want to raise the TA back up at the same time by adding soda ash to bring up the PH. Thoughts? Unable to aerate with a compressor. Thx.

 

[AftonJeeper]

Hi and welcome to the forum. Borax has less of an effect on TA than soda ash does so I would not use the soda ash. You need to be careful when lowering TA, it is important not to go below 7.2 for pH. Read up on how to lower TA here.

 

[Foxy]

"about half of what you expect..." Are you not using PoolMath to figure out what you need to do to change your levels? 4 gallons of what percentage MA? PoolMath says you would have needed 129oz of 31% MA or 280oz of 14% MA to go from 7.6 to 7.2.

Also, you do realize that your trichlor pucks are going to bring your CYA level back up and require another drain and fill, right?

 

[domct203]

"about half of what you expect..." Are you not using PoolMath to figure out what you need to do to change your levels? 4 gallons of what percentage MA? PoolMath says you would have needed 129oz of 31% MA or 280oz of 14% MA to go from 7.6 to 7.2.

Also, you do realize that your trichlor pucks are going to bring your CYA level back up and require another drain and fill, right?

Not sure how you came up with 129oz. With a TA of 175ppm and no borates in the water, you only need 92oz of 31.45% (or 185oz of 15.7%) muriatic acid to go from 7.6 to 7.2, which only lowers TA about 13ppm.