lowering PH with out lowing TA

jlee1414

New member
Sep 20, 2007
1
#1
I'm new to a pool ownership . Currently I am trying to lower PH without lowering TA.
Currently my readings are:
PH 7.8
TA 70
CYN 70
FC 5
CH 230
TDS 1100

When I add acid to the pool I end up lowering my TA to about 40-60 and my PH to 7.4. Then I add Sodium Bicarb to raise the TA to about 100 and up goes my PH. When I add sodium bicarb it raises my TA along with my PH. How can I maintain my PH at 7.2 -7.4 and my TA at 80 - 120 ?
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
#2
When you lower PH, TA will always go down. There isn't any way around that. But when you add baking soda TA should go up much more quickly than PH, so that when you add acid to bring the PH back down you should have gained some ground on TA.
 

Poseidon

Well-known member
May 24, 2007
148
Houston, Texas, USA
#3
jlee1414 said:
I'm new to a pool ownership . Currently I am trying to lower PH without lowering TA.
Currently my readings are:
PH 7.8
TA 70
CYN 70
FC 5
CH 230
TDS 1100

When I add acid to the pool I end up lowering my TA to about 40-60 and my PH to 7.4. Then I add Sodium Bicarb to raise the TA to about 100 and up goes my PH. When I add sodium bicarb it raises my TA along with my PH. How can I maintain my PH at 7.2 -7.4 and my TA at 80 - 120 ?
That's odd. Sodium bicarbonate should raise the TA by 30 points, while raising the pH by just .1. Are you sure you are using sodium bicarbonate, and not soda ash or something else?
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
#4
JasonLion said:
When you lower PH, TA will always go down. There isn't any way around that.
For practical purposes, this is correct, but in commercial pools one can add carbon dioxide to the water to lower the pH with no change in TA. It's the exact opposite of outgassing. Over time, these pools do tend to rise in TA due to evaporation and replacement with fill water that contains some TA unless they have a lot of splash-out or backwash and fill water that is lower in TA than the pool.