Sodium Bicarbonate (Baking Soda) or Sodium Carbonate (Soda Ash) and other water parameters and additions needed

[fabsroman]

Got my SWG up and running yesterday. FC went from 3.0 yesterday morning to 7.0 today running the IC40 on high for 24 hours. CC went from 1.0 to 0.5 or less.

Pool is around 37,000 gallons

Today's tests resulted in:

FC - 7.0
CC - 0.5
TA - 20
CYA - 20 but still have some in the skimmers and planning on adding another 9 pounds once this is all dissolved
PH - 6.4
Salt - 3,400

Debating whether to add baking soda to raise the ph or soda ash to raise both the ph and the alkalinity. Any advice on which of those two to go with, and what else I should be thinking about adding?

 

[mknauss]

How did your pH and TA drop so low? How did you test a pH of 6.4?

Soda ash is a good idea in your case. Use a starting pH of 6.8 (lowest the K1000 can test) and target pH of 7.4. Looks like about 3 1/2 pounds of soda ash.

Be aware soda ash raises pH but really raises TA.
Also, the CYA you are adding is lowering your pH.

 

[PoolGate]

Marty - This is a pool that had an ammonia issue and took like 50 gallons of 10% bleach to neutralize.

 

[fabsroman]

How did your pH and TA drop so low? How did you test a pH of 6.4?

Soda ash is a good idea in your case. Use a starting pH of 6.8 (lowest the K1000 can test) and target pH of 7.4. Looks like about 3 1/2 pounds of soda ash.

Be aware soda ash raises pH but really raises TA.
Also, the CYA you are adding is lowering your pH.

Sorry for getting back to this so late. As Poolgate mentioned, this pool required 50 gallons of 10% pool chlorine to get rid of the ammonia issue. In the process, the ta and ph became what it is. I measured the ph with an aquarium test kit and that is how I was able to test down to 6.4. I added a single box of Arm & Hammer soda ash, which is somewhere between 3 and 4 pounds of the stuff. I have not tested the water again since adding it yesterday, but will test the water probably tomorrow to see where I am at ph, ta, cya, fc, and cc wise. I tested for fc and cc yesterday and had fc at 15ppm and zero cc. So, I have cut back the chlorine production from the SWG.

 

[mknauss]

Sounds good.
If your pH has gotten to 7 or so I would switch to baking soda to raise the TA up to 70 ppm.