TA lowering issue

[Msch99]

Hey all,
Working on lowering my TA the last several days. Hooked up the original pump we had replaced with sand filter and shooting it over the pool to speed along the PH rise. Sand filter pump is 3k gph and the original pump is 2.5k gph rated.

Besides bad acid and bad testing operator, is there anything that would prevent TA from dropping below 100?

Accidently opened muriatic acid yesterday that wasn't the 20 baum but the weaker stuff. no splash etc.
Started the day at TA 130, ph 7.5+, ended the day at 120.

Test at 730am today
PH 7.5
FC 6
CC 0
CH 200
TA 120
CYA 70
Not sure about salt, ran out of strips and waiting on test kit, but low salt light isn't lit on the swg.

Added 20 oz 20 baum (32%) Muriatic acid instead of 42oz to start sneaking up on target of 80 or so TA.

Tested at 1015am down to 110
Tested at 3pm, ph up to 7.5 and TA down to 100.
Wife and friend were swimming / using leaf rakes due to leaving pool uncovered for aeration.

Added another 20 oz 20 baum (32%) Muriatic Acid at 430pm after they got out. We had 6 tenths of rain ~ 5pm, pool uncovered.
Test at 815pm ph at 7.2, TA still at 100. tested twice, same result.
Thanks!
Mike

 

[needsajet]

Nice to meet you via TFP

It can take quite a few hits with acid to reduce TA, and it appears that the method is working for you. Taking it down to pH 7.0 each time may hasten the process a wee bit.

If there's top-up water being added that has TA (most water does), that might explain the upward pressure on TA.

The only reason to lower TA is if required acid additions are more frequent than you're able to fit in. Otherwise, you can just maintain pH around 7.5 to 7.8, even letting it ride around 7.8 for extended periods.

 

[Richard320]

Some thoughts:

1) Check for static charge on the tip of the R-009. How? Easy. Just wipe the tip off with a damp paper towel before each drop the next few tests. If the TA test starts behaving, you had it. If nothing changes, what are you out- a couple paper towels and twenty seconds of your life?

2) Plug your numbers into poolmath to get the acid dose and then plug that in at the bottom where it says Effects of Adding Chemicals. It'll tell you how much you can expect TA to drop. You may discover the drop is small enough it might not register on the TA test. Note that when it calculates pH drop, it will only be accurate within a very narrow set of parameters. I just ignore that part. The TA drop calculation has always been spot on for me, though.

3) If I had a spare pump lying around rigged up as an aerator, I think it would get repurposed into a water cannon when I was done with the gentle shower.

 

[Msch99]

Thanks Richard.

Yup, made the mistake of not wiping the dropper early on when I tested myself against the TA standard, you set me straight there. grin/wink

I played with the effects calculator yesterday and yes it showed a change of 7.8 for 20 oz MA, which wouldn't be picked up. I thought the calculator wasn't working because when I put 60oz into the pool the first day it dropped 60 TA and calculator says a drop of 23. The next addition of 40oz also dropped ~ 50.

It looks like the effects calculator only uses the gallons in pool for its calculation?

Maybe the lower the TA the more MA needed to see a drop?

Anyway, I will keep plugging away as time allows.

Next step is to see how much my undersized swg actually puts out. The manual says 5.5gr/hr. Could do some calculating I guess, but thinking to set it for 8 hrs at normal rate overnight and see what happens. (FC,CC test when cover up and first thing in am)

Ok I will bite...what is a pool cannon?

Thanks!
Mike

 

[JamesW]

The TA drops the same amount per amount of muriatic acid regardless of the TA.

The pH drops more at lower TA for the same amount of acid.

 

[Richard320]

Ok I will bite...what is a pool cannon?

Thanks!
Mike

Water cannon. You've never seen news stories of protestors being knocked off their feet by a stream of water?

Do a googl;e image search on "water cannon" for inspiration