Is there anything wrong with low TA if LSI is good?

[M28]

I have a 14k gallon indoor plaster pool. Right now I have the following:

- 3 ppm Free Chlorine
- 7.9 pH
- 35 40 TA
- 390 Calcium
- 0 CYA
- 1400 ppm Salt
- Temperature around 65~95 depending on whether I wanna swim
- LSI: -0.02 ~ -0.13

Swimmer load is typically very low. If I don't do add anything to the pool, I only need to add a bit of chlorine every week or two to maintain that range (very little direct sunlight). TA seems to settle around that level, and pH as well. That pH is a little higher than most people like to keep it at, but considering my chlorine levels and the fact I don't need any CYA, it seems still effective at sanitizing.

Conventional wisdom is to keep TA higher, but if I do, I'm forced to constantly add acid to keep ph at an acceptable level to keep LSI good. The current balance is very stable requiring minimum intervention.

The question is: am I doing something wrong? Could this chemical balance come to bite me later?

 

[PoolStored]

Indoor pools have less CO2 off-gassing (which drives pH up in outdoor pools), so a lower TA can still buffer pH effectively. You are not using lots of products that change pH (acid, CYA etc.), so it is likely you have enough buffering capacity for your pool. If it is stable, leave it.

 

[ajw22]

Welcome to TFP.

How do you measure a TA of 35?

 

[M28]

Welcome to TFP.

How do you measure a TA of 35?

3 drops is very very close to the threshold color, but not quite. 4 drops is definitely there. I'm fairly sure 3.5 drops would achieve the same color. I'm calling that 35, but if we were to adhere to the test strictly, I guess we'd call that 40.

 

[ajw22]

3 drops is very very close to the threshold color, but not quite. 4 drops is definitely there. I'm fairly sure 3.5 drops would achieve the same color. I'm calling that 35, but if we were to adhere to the test strictly, I guess we'd call that 40.

It is 40 if that is the point where you get no further color change.

The fifth drop gives no further color change?

You are not being asked to judge a threshold color.

 

[M28]

It is 40 if that is the point where you get no further color change.

The fifth drop gives no further color change?

You are not being asked to judge a threshold color.

Okay now that is settled, let's focus on the actual question

 

[PoolStored]

Okay now that is settled, let's focus on the actual question

Indoor pools have less CO2 off-gassing (which drives pH up in outdoor pools), so a lower TA can still buffer pH effectively. You are not using lots of products that change pH (acid, CYA etc.), so it is likely you have enough buffering capacity for your pool. If it is stable, leave it.

 

[M28]

Alrighty. If that is the consensus then the question is also settled

 

[PoolStored]

consensus

Consensus of 1. You are fine.

 

[ajw22]

You are more fine with a TA of 40 then 30.

 

[JamesW]

If you had CYA, I would want a higher TA to keep the carbonate alkalinity in a good range.

With no CYA, the low TA is less of a concern.

I would probably stay at 40 to account for a margin of error.