Combined Chlorine?

[mdlinkous]

OK... So I just bought a good professional tester... Lamotte ColorQ Pro7... this is a classic example of how cheap test kits/strips can fool you. I always have thought I kinda understood pool chemistry but was never able to test for Total Chlorine. I have been getting a good education on understanding how pool chemistry works.

My results are astonishing.... Can this be right. My water is clear but my Free Chlorine is reading 2.20 (which I knew) but my total chlorine is 5.0... so this means my Combined Chlorine is 2.8... so this means I need to SLAM... bad!

I was so "shocked" I repeated the test with the same results.... WOW is all I can say?

 

[YippeeSkippy]

Oh darn, Mdlinkous. We only recommend two different kits for testing, the TF-100 or the Taylor K-2006C. Both use the same Taylor reagents but the TF-100 is a better buy cause of the quantity of reagents it provides for the tests we do most often.

Many folks have tried using the Lamotte tester and found it gave varied test results on the same sample and also required frequent calibration. We don't endorse it.

Pool School - Test Kits Compared

Maddie

 

[Richard320]

If you've been using any monopersulfate shock, it will affect the readings. See page 21 under interferences. http://www.vendart.com/images/pdf/ColorQ_Testing_Tips.pdf

 

[mdlinkous]

I am correct, though, right? My combined chlorine is calculated by subtracting Free Chlorine from Total Chlorine? I will eventually get the CC down to <0.05, right?

 

[pooldv]

Yes, FC plus CC equals total chlorine.

With CC that high a SLAM Process is definitely needed.

 

[AUSpool]

...
Many folks have tried using the Lamotte tester and found it gave varied test results on the same sample and also required frequent calibration. We don't endorse it.
...

The ColourQ cant be calibrated, not in the way we calibrate a pH or salt meter with standard solutions. It has a 'blank' function which I think many are confusing with a calibration function. The first proceedure in the test sequence is to do a 'blank' on the water sample which all following tests are then compared to.

Mdlinkous, the worst feature for you is the FC range at 0 - 10ppm which will make a SLAM hard to manage and with a CC of 2.8ppm I really think that's what you need. Diluting a sample with 50% distilled water will give you a rough estimate to 20ppm. You will need to use you current CYA level and the CYA/FC chart to get your target FC slam level.