High alkalinity, perfect pH

[mavrick6382]

Hello, this morning around 8a I tested my water and found that my pH and TA were high at 8.0+ and 230 respectively. I used Pool Math to calculate the appropriate amount of muriatic acid to lower the pH to 7.1; that amounted to 134 ounces of acid. The plan was to aerate after that to bring pH up. At about 5:30p this evening I re-tested. pH is at 7.5 but TA is still high at 200.

Any recommendations? Should I keep adding muriatic acid until the TA is low enough?

 

[Texas Splash]

Should I keep adding muriatic acid until the TA is low enough?

You probably will need to, but not simply to hit a specific TA number. There are two concerns about managing TA.
1 - In certain areas, the southwest for example, water is generally hard, so your CH can rise quickly. So if the CH is elevated, let's say 500 or more, then controlling the TA and pH are crucial to preventing scale. Make sure to enter all your test results in the PoolMath tool and pay attention to the "CSI" row.

2 - The other part of managing the TA is watching to see how quickly the pH rises throughout the week. Typically, if the TA is elevated, the pH will rise quicker. So doing the acid/aeration method helps to lower the TA over time. With a TA of 200 now, I suspect you'll probably want to let the TA drop to at least 100, perhaps even lower at some point if it helps slow the rise of pH. Let the pH rise to about 8.0 before hitting it with acid and lowering it to about 7.0-7.2. You should see good results that way.

So continue with what you are doing, but use the PoolMath tool to monitor your "CSI" progress so that can see what's happening overall. Hope that helps.

 

[ajw22]

PoolMath Effects of Chemicals says 134oz of MA lowers pH by 1.9 and TA by 31. Just about what you got.

Wait until the pH gets up to 8 to do another cycle or aerate to raise the pH.

 

[mavrick6382]

Just re-tested chemicals and here's what I got:

FC = 6
pH = 8
TA = 250-260
CYA = 55
CH = 0 (I use a Taylor K-2006 kit. After adding R-0011L, sample did not turn red. This is mind blowing given the hard water we have in AZ)
Salt = Unknown (don't have test kit); used 0 for CSI calc
Borate = Unknown (don't have test kit); used 0 for CSI calc
Pool Temp = 76
CSI = Doesn't register

Is the CH throwing anything off?

 

[ajw22]

Test your house water pH, TA and CH.

On the CH test, you added 10 drops of R-0010 before you added 3 drops of R-0011L?

The solution should turn red, pink, or blue. If the sample turns blue, you are done and your CH level is zero.

CH is independent of other tests and doesn't throw anything off.

You don't have borates if you did not add it.

Your CYA is 60. We round up. With a CYA of 60 your FC should be 7-9. See FC/CYA Levels

 

[wireform]

Are you using old regents?

 

[mknauss]

Or softened water?

 

[mavrick6382]

House Water Test (water is softened)
pH = 7.8
TA = 140
CH = 25

Answers to above questions:
- I added 20 drops of R-0010 before adding 5 drops of R-0011L. That's what the test kit calls for (https://edc.poolsupplyworld.com/wpdf/Taylor K-2006 Test Kit Instructions.pdf)
- The reagents for the CH test are 3.5 years old (they are still the originals from when I bought the kit)
- Pool water is not softened

I originally did this test outside (tonight) under a flood light. After taking the sample indoors, turns out the water sample was in fact light pink. Took 60 drops to turn it very light blue, so 600 CH. New Pool CSI = 1.15. I was told last year on this forum that it should be -0.3 to 0.0.

Sounds like it might be time for a pool drain? I drained the pool August 2018. It also sounds like I need to hit it with more acid and lower the pH to about 7.0-7.2.

 

[ajw22]

Time for a fresh set of reagents. They are in sale at Complete Refill Set for TF-100-ON SALE NOW