Confused about testing for TA

Xebec

Active member
Jun 23, 2008
32
#1
I just switched to a liquid based tester from strips.

I'm fine with testing clorine and ph, but I'm really confused about Total Alkalinity.

The instructions say to add the initial drop(s), then count the drops of another type until there's a "permanent color change".

What does that mean?

I tried it and had a purple color, initially. I kept adding the other drops and finally the solution turned clear. I'm really confused.
 

Rangeball

Well-known member
May 25, 2007
785
#2
Depending on the test kit you have, the color change you are looking for varies, but should be indicated in the directions.

Make sure you are adding 5 drops of the indicator as stated, then count each drop of titrant, swishing the sample after each drop, until the color changes to what is stated in the instructions. Multiply the # of drops it took to get the change by 10 and that is your TA level.

I use the HTH 6 way kit from Walmart, and the 5 drops make the sample green, and turns red after enough titrant is added.
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
#3
They say "permanent" because sometimes the color will start to change when the drop first hits the sample, but as you mix it will go back to what it was. The color change should remain steady through at least 15 or 20 seconds of swirling.
 
G
#4
Xebec said:
I tried it and had a purple color, initially. I kept adding the other drops and finally the solution turned clear. I'm really confused.
You have an inexpensive test kit. the color change from blue to pale yellow is not aways easy to see. My suggestion is to get a better test kit that uses a combination indicator that changes from green to red for the TA test. It will make your testing much easier. Two examples of such testkits are the Taylor K-2006 and the TF100.
category/pool-school/pool_test_kit_comparison
 

piku

LifeTime Supporter
Mar 12, 2008
259
Hatfield, PA
#5
If you want to go cheap, the walmart hth 6 way does as well. In fact the only limitation of this kit is that it tests for total hardness rather than calcium hardness and has only an OTO chlorine test. The reagent sizes are also rather small. But it's good in a pinch and I have one just because.