Detection limit for Wal-Mart kit CH test??

[waterbear]

If you are testing the TC with the OTO test in the walmart kit be aware that OTO is not the most accurate test to read. It is possible that your TC was higher. The test takes about 2 minutes to develop fully.

[Henrys514]

I usually wait 2 minutes before doing the reading. So if I keep adding indicator, if I have no hardness, the water will eventually turn blue. If I do have hardess, it will turn pink (instead of purple like the instructions say), and then I titrate from pink to blue, then multiply drops by 50 to get my reading?

[waterbear]

I usually wait 2 minutes before doing the reading. So if I keep adding indicator, if I have no hardness, the water will eventually turn blue. If I do have hardess, it will turn pink (instead of purple like the instructions say), and then I titrate from pink to blue, then multiply drops by 50 to get my reading?

Basically, yes. The color is sort of a pinkish magenta when hardness is present and blueish when there is none.

[Henrys514]

Ok, thanks. I'll try that tomorrow and see what happens. Oh yeah, and I'll work on getting a better test kit too.

[prh129]

I had a similar problem with the CH test in the WalMart (HTH) 5-way test kit. My TC was in the 3-5 ppm range at the time and the hardness was actually pretty low (10-20 ppm) but the solution turned yellowish when I added the 5 drops of the dark reagent. The CH test in Ben's kit worked without a problem.

Peter

[Henrys514]

Well, i tried the test yesterday...My TC was 5ppm+ (I did some dilution, and got about 9ppm). With 8 drops of the indicator, the water turned this funny pinky yellowish color, so I titrated as usual and got 250ppm CH. I will test again today after work and see what I get. I can hopefully add some calcium today if the rain stops.

[waterbear]

250 ppm CH is fine. Why add more?