Alkalinity keeps rising

[wkussmaul]

Hi all,
My trouble-free pool is doing great under the BBB method, in general.
However:
I have noticed that the TA is high (tends to want to be ~125-130).
I add acid. Ph and TA go down, then I aerate to a higher pH-- at which point the TA is right back up there again.

Here are a series of test results (CH constant at 270, CYA 46, FCL/TCL hovering 2.0-4.0 as I add daily bleach):

day 1: pH 7.6 TA 134 => add acid
day 2: pH 7.0 TA 89 => aerate for a day
day 3: pH 7.3 TA 84
day 4: pH 7.4 TA 125

It's as though there is a source of alkalinity; like my 4-year old plaster is still curing, or something.
Is this a problem? Or do I just keep adding acid?

:?:

 

[coffeegoddss]

I don't know about the plaster but have you tested the water you put into the pool? I battle high TA and, for giggles, decided to test what comes out of the hose. The TA was 290! So every time I top off the pool an inch or two, I'm adding to the TA. It's a never ending battle - but I think I've finally gotten it under control. Now that I know what's causing it, I can correct it pretty quick.

 

[JasonLion]

Have you been adding water to top off the pool? Fill water is a common source of TA in some areas.

Lowering TA is a fairly slow process. Give it time and it will work.

Also, what test kit are you using to get those test results. None of the tests which give results +-1 are actually any where near as precise as they imply that they are, and you actual levels are likely to be noticeably different than the results returned by those tests.

 

[HouTex]

Similar issue here. Just this week my TA went from 50 back up to 70 over a 5 day period with NO added water. I wonder if a temporary drop in TA is normal after an acid addition? My TA will always drop 10 to 20 ppm about a day after an acid addition. Two or three days after that it's back up, but it does not continue to rise above 70. I can't imagine it's a problem with my circulation. With my 2 HP pump I get a complete turnover every 1.5-2 hours.

 

[JulieS]

I just asked this same question in another thread! I am not adding water at all, once my TA is in range, a day later it is back to 170-180. The TA of the water I used to fill is 270, but once I get it down, shouldn't it stay down? I understand that if I add more water it will go up, but with just normal conditions it shouldn't... right?

I have had to back fill one time, I used a standard garden sprinkler to aerate as I filled, it helped bring my pH up so that I could add the acid to lower the newly raised TA!

 

[wkussmaul]

To all who replied,
Thanks.
I will test the fill water, should have thought of that.
But, in the above series of test results, no water was added.
My tester is the Lamotte ColorQ.

 

[dschlic1]

I have noticed that if it rains after a period of dry weather, the TA in my pool will increase. I believe it is the dust and diry washing off of everything.

 

[JasonLion]

The ColorQ's alkalinity test is +-15 in the relevant range when everything is working correctly.

I suspect the Day 4 result might be wrong. It will be interesting to see if that increase continues or the number drops down the next time you test it.