Higher TA and test strips

[Heckpools]

i personally like keeping the TA a little high 120-150. Helps keep the Ph from bouncing. again this is just my 2 cents and what i like to do. and ive never had any problems with doing so.

guys- i use the aquachek silver test strips with all my customers pools. since ive gotten here ive seen ALOT of talk about how strips are bad.

are they really that far off as far as the readings go??

thanks

 

[chem geek]

Re: Adding Muriatic Acid to bring TA down

It really depends a lot on the specific pool and how much aeration or churning of the water there is, but having a higher TA and using hypochlorite sources of chlorine (bleach, chlorinating liquid, Cal-Hypo, lithium hypochlorite) will most certainly tend to make the pH rise faster. Having the TA lower, usually at around 80 ppm for pools, works much better. This benefit is most especially seen in saltwater chlorine generator (SWG) pools.

There is clear science that explains this effect, but I won't get into that here. Pools are essentially over-carbonated and that's what TA is mostly measuring. Just as when you stir up a carbonated beverage, the carbon dioxide outgasses, the same thing happens in a pool and this process makes the pH rise with no change in TA. You need to think of bicarbonate (baking soda, Alkalinity Up) as having TWO effects -- one which increases pH buffering and another which increases the tendency for the pH to rise. The latter effect is more dominant at higher TA levels.

If you are using acidic sources of chlorine, such as Trichlor pucks, then a higher TA is definitely recommended and helps to stabilize the pH in two ways. First, the higher TA does buffer the pH more, but also the greater outgassing of carbon dioxide makes the pH rise which counteracts the pH drop from the Trichlor. In theory, you can set a TA high enough to have a perfectly stable pH with the only effect being a TA that gets lower over time (so needs baking soda or Alkalinity Up to raise it).

Richard

 

[Guest]

Re: Adding Muriatic Acid to bring TA down

i personally like keeping the TA a little high 120-150. Helps keep the Ph from bouncing. again this is just my 2 cents and what i like to do. and ive never had any problems with doing so.
This works if you are primarily using stabilized chlorine, which is acidic. If you are using unstabilized chlorine then this can lead to pH INSTABILITY.

guys- i use the aquachek silver test strips with all my customers pools. since ive gotten here ive seen ALOT of talk about how strips are bad.

are they really that far off as far as the readings go??

thanks

in a word, Yes! The biggest problem is their precision. For example, the TA test has a precision of 40 ppm....this is WAY to big to try and make water balance adjustments. Strips also can only test total hardness and NOT calcium hardness....not a vaild test for plaster pools! Total hardness is going to be higher than calcium hardness and this could lead to agressive water if this difference is not taken into account. I won't even go into the CYA test on strips but just let it be said that the results bear NO resemblance to reality!
As for pH, the strips have too wide a range between graduations and too small a color change to make reading them easy.
also, with just about every test development time is critical. The colors tend to change more as time passes so if the test is not read at just the right time you results are going to be off (often by quite a bit).

The only test on the strips that is useful, IMHO is the chlorine test. Also, borate annd salt test strips are very good cost effective choices for their intended uses. Other than these specific tests the strips don't have much to offer.

 

[Heckpools]

CHEMGEEK- i do use trichlor so im glad keeping the TA a little on the high side is ok... you are one smart dude..

WATERBEAR- im going to sound pretty stupid but i never even noticed it said TOTAL hardness and that didnt mean total calcium hardness


thank you both!!

 

[Guest]

CHEMGEEK- i do use trichlor so im glad keeping the TA a little on the high side is ok... you are one smart dude..
I second that!

WATERBEAR- im going to sound pretty stupid but i never even noticed it said TOTAL hardness and that didnt mean total calcium hardness
Most people don't--or don't realize that they are different tests. They only reason one would want to test total hardness in a pool is if you are using the Hamilton Index for water balance (Designed by Jock Hamilton of United Chemical). IMHO, it leaves a lot to be desired. Hamilton index is not based on anything other than empirical observation and allows pools to run at much higher pH (8.0 or even higher) and still be "balanced". Interestingly, most of United Chemical's bromine based products require a high pH to operate properly!

Coincidence? I think not!