Testing kH and gH

[Flex26]

I have a really silly question about using the AP kH/gH test kit (link below). The instructions say to add one drop to the test tube and shake up. You must continue adding one drop at a time until the test water turns a certain color. I can't remember which color was which, but one of the tests was green. My question is this: at what shade of green should I stop testing the water? After a few drops, the water turns a light green, then gradually gets darker. When do I stop?

Does anyone else have a preferred method of testing kH and gH?



http://www.bigalsonline.com/cgi-bin/view.cgi

 

[Lou]

I think when the color changes that's it...any green that stays in the tube. Usually when you get close the drop shows green and disappears when shook, but then eventually it won't disappear and that's when you stop.

 

[Somonas]

Yep, as soon as the colour changes that's it.

It gets tricky when you have less than 1 degree of KH or GH (and then you just use a test tube with twice as much water, and divide the resulting number of drops in half) this is also handy if you want to verify your accuracy.

 

[Lotus]

The KH test should turn from blue to yellow, and the GH should turn from clear to green.

Count the drops, and the first drop where the water turns green on your GH is the reading.