Should I Lower TA Slightly

[JM7]

I have a 10K gallon pool in AZ. I use a combination of bleach, trichlor, and dichlor to manage the CL. I can’t solely use liquid chlorine because I am not there on a day to day basis. Here are my numbers from this morning:
FC=3
CYA<30
PH=7.6
TA=90
CH=240
I want to keep my PH in the 7.4-7.6 range, no higher, in order to minimize tile scaling. Almost always, when I get my PH down to my desired range, it rises back up to the 7.7-8.0 range within a couple days. Here’s my question….Should I lower my TA from 90 to 80 in order to see if the PH rate of increase will slow for me?

 

[Texas Splash]

A CH of 240 in AZ? Wow. Don't see that very often. You do have the option to lower the TA a bit more. In fact, you could go as low as 50-60. The tabs are acidic so they may try to pull the TA a bit lower too. Just be mindful of your CSI (use the PoolMath APP0 to ensure the water doesn't get too aggressive for your plaster.

On a side note, with temps warming up watch that FC and CYA. Your water will need much more UV protection than a CYA of 30, and the FC will burn fast.

 

[Rancho Cost-a-Lotta]

The TA of your fill water is a significant player in TA maintenance, particularly during swim season when evaporation is at its highest. Test the TA of your fill water to give you idea of how it will effect TA over time.

 

[pjt]

I want to keep my PH in the 7.4-7.6 range, no higher

That's almost impossible.

Should I lower my TA from 90 to 80 in order to see if the PH rate of increase will slow for me?

If you can, work your TA down to 50-60 and your pH will likely settle in the high 7s, which is perfectly fine. Manage the other element of CSI, not just pH.

What's the TA and CH of your fill water?

What model test kit do you have?

Priority should be bumping up your CYA with a commensurate increase in FC.

 

[JM7]

The TA of your fill water is a significant player in TA maintenance, particularly during swim season when evaporation is at its highest. Test the TA of your fill water to give you idea of how it will effect TA over time.

Excellent point to keep in mind. Fill water TA is 120. Pool was fully drained and filled last month.

 

[JM7]

That's almost impossible.


If you can, work your TA down to 50-60 and your pH will likely settle in the high 7s, which is perfectly fine. Manage the other element of CSI, not just pH.

What's the TA and CH of your fill water?

What model test kit do you have?

Priority should be bumping up your CYA with a commensurate increase in FC.

There’s not really anything else I can manage except TA and PH. Fill water TA is 120, fill water CH is 240, and fill water PH is 7.7. Test kit is Taylor K-2006. As stated above, I have to manage CL with stabilized chlorine most of the time. When I’m in town, I use liquid. Hence the low CYA for now. It will be creeping up quite a bit in the next few months from the dichlor and triclor. I have no choice with that.
So, from a technical standpoint, why is it “almost impossible” to keep PH in the 7.4-7.6 range? I’m finding it difficult for sure without adding acid ever day. That’s why the question about lowering TA.

 

[Rancho Cost-a-Lotta]

This will help keep pH and TA in check while out of town...

The tabs are acidic so they may try to pull the TA a bit lower too.

If you plan on staying in the house long enough to realize a ROI, consider a SWCG.

 

[pjt]

There’s not really anything else I can manage except TA and PH.

You can also manage CH, which is especially important given the CH of your fill water. Look into getting a water softener for your fill line.

So, from a technical standpoint, why is it “almost impossible” to keep PH in the 7.4-7.6 range?

Might be possible temporarily using trichlor (which is acidic). However, that's not sustainable for long term chlorination. The only two long term viable methods are LC and SWCG (which I would highly recommend). With TA on the low end (50-60), pH will stabilize in the high 7s, not 7.4-7.6. Every pool is a little different.

PH TA Relationship - Further Reading

www.troublefreepool.com

I’m finding it difficult for sure without adding acid ever day.

Yes, I think you can see how hard it would be. Let the pH stabilize in the high 7s.