Runing TF 100 CH Test

Total hardness and calcium hardness in pool water.
Scale, calcium buildup, hard water and scaling problems.
Conehead396
Pool Newbie
Pool Newbie
Posts: 5
Joined: Mon 08 Jun, 2009 21:12
My Pool: 24 X 52 above ground with Aqua trol SWG
Location: Virginia

Runing TF 100 CH Test

Postby Conehead396 » Thu 23 Jul, 2009 20:09

I have the TF 100 test kit and have been happy with it other than I cannot seem to get the CH test down.

Pool store will show 220-260 and i will get 400-420. I do have .3 copper and I am following the direction to account for this.

I know the pool stores test or off. But by almost 200?

Thanks for any suggestions.


chem geek
Pool Industry Leader
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Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Runing TF 100 CH Test

Postby chem geek » Thu 23 Jul, 2009 22:09

Are you swirling between each drop for 30 seconds (waterbear's recommendation) or at least a substantial amount of time? It sounds like you are already adding some titrant drops to start with (due to metals), which is good. The test requires very thorough mixing to be accurate. Use of a magnetic stirrer makes the test go much faster. You can use a 10 ml sample size where each drop is 25 ppm instead of a 25 ml sample size where each drop is 10 ppm -- that will at least make the test go faster while waiting between each drop and will give you another ballpark number.

Nevertheless, if one doesn't wait between drops, then if anything one measures too low a number, not too high so your number is likely to be more accurate. I would trust your number over the pool store number. You could go to another pool store for a separate check, if you like.
Conehead396
Pool Newbie
Pool Newbie
Posts: 5
Joined: Mon 08 Jun, 2009 21:12
My Pool: 24 X 52 above ground with Aqua trol SWG
Location: Virginia

Runing TF 100 CH Test

Postby Conehead396 » Fri 24 Jul, 2009 05:37

Thanks, I did not know about the 30 seconds. I will try that. I may take my kit to work and see if we have a small magnetic stirrer. We have them but I don't know if they are that small.


Thanks again.
chem geek
Pool Industry Leader
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Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Runing TF 100 CH Test

Postby chem geek » Fri 24 Jul, 2009 11:17

This stirrer isn't cheap, but it's small and designed for such tests. As I said, I suspect you'll still get a similar result and that the pool store test is wrong. Some types of tests they use read falsely low if the CH is higher (waterbear at Trouble Free Pool knows more about that).
Conehead396
Pool Newbie
Pool Newbie
Posts: 5
Joined: Mon 08 Jun, 2009 21:12
My Pool: 24 X 52 above ground with Aqua trol SWG
Location: Virginia

Runing TF 100 CH Test

Postby Conehead396 » Fri 24 Jul, 2009 23:17

I took my test to work and got a 380 CH using the stirrer. I even got one to take home. The girl in the lab had a junk drawer with old ones that she was using for parts, and my boss let me have one that still works. Looks like hell, but works fine.

Thanks again

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