Quick TA and pH testing questions

[Malka]

Hi!
I maintain 2 private indoor spas. Thanks to TFP, I have been able to test the water and maintain safe sanitizer levels. We also solved our cloudiness issues.

The filter runs about 12 hours/day, in 2 sessions. I realize the aeration from the filter might effect pH.

got my TA up to ~90
pH keeps spiking to 8.2 (or higher?)
Is it normal to be adding acid a few times a week?
Can I ignore TA (let them fall at 40-50), if my pH is in the normal range? I just watched the TFP video on the lower TA recommendation. Does that apply to bromine pucks also?

I learned here that MPS messes with my dpd readings, so I’ve been using liquid bleach as a shock a lot. Would prefer to use MPS.
Any way to calculate the effect, either in level or duration? Is it worth it to get the MPS interference remover vs just using bleach

The hardness is very low (75, 100) on both. Can I use the hardness increasing stuff on the same day as other chemicals?

Thanks so much!

 

[jseyfert3]

The filter runs about 12 hours/day, in 2 sessions. I realize the aeration from the filter might effect pH.

Aeration will always cause pH rise for normal pool water. Spas especially suffer from pH rise as they have a large amount of aeration from large pumps causing lots of water circulation and especially the air that most spas add to jets. The higher the TA the faster the pH rise.

ot my TA up to ~90
pH keeps spiking to 8.2 (or higher?)
Is it normal to be adding acid a few times a week?
Can I ignore TA (let them fall at 40-50), if my pH is in the normal range? I just watched the TFP video on the lower TA recommendation. Does that apply to bromine pucks also?

A quick search shows that bromine pucks are acidic, but I'm not sure to what extent. I have no first hand experience with bromine. Me, and most here, just use chlorine. In general if you aren't letting the TA drop lower than that, and the pucks aren't pulling it down, you should be fine. Just be sure to keep a close eye on the pH. I wouldn't completely ignore the TA, as you do not want zero TA, but yes pH is the more important one.

Adding acid a few times a week is completely normal.

I learned here that MPS messes with my dpd readings, so I’ve been using liquid bleach as a shock a lot. Would prefer to use MPS.
Any way to calculate the effect, either in level or duration? Is it worth it to get the MPS interference remover vs just using bleach

I'm sure it could be calculated, but that's well beyond me. The tradeoff of MPS interference remover vs just using bleach is up to you.

On a somewhat related note the reason I went chlorine over bromine was because I thought to myself "if I have to add MPS or chlorine to a bromine spa, why do bromine at all when I could just add chlorine and be done with it?"

The hardness is very low (75, 100) on both. Can I use the hardness increasing stuff on the same day as other chemicals?

Yes. Just make sure it fully dissolves before adding other stuff.

Keep an eye on your CSI with a low CH like that, especially when you let that TA drop down to 50.

 

[Malka]

Thanks for your help!