Total Hardness Results in 6-Way Test Kit


Active member
May 3, 2020
SW Michigan
Hello TFP friends,

I purchased a HTH 6-Way Test Kit, and here are 5 of the 6 results;
Total Chlorine = 5ppm
pH = 7.6
Alkalinity = 80ppm
CYA = 40ppm

My question is related to the total hardness results. The test calls for 5 drops of the hardness indicator and it should turn red if hardness is present. I'm puzzled by what I should be seeing and what the results might indicate.
When I add each drop it turns red momentarily and when I swirl it disappears. It takes 10 drops (instead of 5) for the water to fully turn red (more like a bright magenta), and 15 drops of the titrant to turn blue.

My pool has a 25 gauge vinyl liner. My water looks and feels great. If I drop my chlorine just slightly to get it in the ideal range could that be enough to impact the TH? And, also, do I need to be concerned about this anyway given I have a vinyl liner and not plaster? The sheet says low total hardness will cause foaming and damage plaster surfaces (neither of which I have).

Thank you as always!


Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
Low CH is of no consequence to you with a vinyl liner. If you see foaming, add 50-100 ppm calcium. You can use calcium hypochlorite to add your chlorine and that will add calcium.

Not sure about the test. That is not a recommended test kit. Also be ware that your chlorine test is TC only and I suspect 5 ppm is max. So that will become an issue if you have any algae or water clarity issues.


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
Since it turns red with 10 drops, I suspect the indicator is bleaching out from high FC. Yes, it's not really all that high at 5 (could even be higher, you know) but lots of people who should know better still preach 1-3 FC is ideal no matter what the CYA is. But I digress. It goes blue at 15 drops, so there's your CH reading. Multiply by whatever factor. If it's low, who cares? You have vinyl not plaster.
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