# GH and KH - Tetra Test Kit



## lokobreed (Dec 30, 2003)

For GH and KH, I have to take 5 ml of wat out of the tank and add one drop at a time and then shake the test vial gently and continue to add drops of the test liquid until there is a color change.

Is it until the water totally changes from one color to the next?
Or is it until the water color shows the first change to the next color?

FOR EXAMPLE: 
KH – you measure how many drops it takes till the water changes from blue to yellow. DO I measure it how many drops it takes to totally change the water color from blue to yellow or do I measure till blue shows the first hint of yellow?

Thanks


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## trenac (Feb 15, 2004)

I count the drops intil the first hint of color change. It usually takes only a drop more to change the color completely.


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## amanda huggenkiss (Mar 3, 2004)

Oooh, I have a question! Do you count the first drop? Say you add a drop and it changes to yellow right away -- does that mean your kh is 1? It should mean your kh is 0, right? So if you put 3 drops in total, does that mean your kh is 3? Or 2?

(not a huge difference either way, but it's always bugged me!)


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## gnatster (Mar 12, 2004)

In the event 1 drop is changes the color I would double the sample volume and divide the results by 2. It is also my understanding the total # of drops is the total kH reading. 

-*-*-*-*
gnatster


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## trenac (Feb 15, 2004)

Amanda... I do count the first drop, so if it changes to yellow with the first drop I would say your KH is 1.


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## ninoboy (Jan 26, 2004)

Yeap, I use Gnatster's way to get decimal reading.


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## malkore (Nov 3, 2003)

you can also be lazy like me, such that at 7 drops it starts to change, but not fully, and the 8th drop makes it change fully...I call it 7.5 dKh.


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## Coltrain (Jun 9, 2004)

malkore said:


> you can also be lazy like me, such that at 7 drops it starts to change, but not fully, and the 8th drop makes it change fully...I call it 7.5 dKh.



Hmm so have i been doing these tests all wrong?? I use the Hagen KH.GH kit but its says that 8 drops of KH is equal to 80ppm with is not 8degress but 4.5 .. is that correct??


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## Rex Grigg (Dec 10, 2002)

Some test kits give degrees of hardness and others give ppm. Use the directions for which type you have.


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## malkore (Nov 3, 2003)

Rex is correct. Some kits 1 drop = 10ppm, other kits 1 drop = 1 degree of hardness.
I should've specified I use Aquarium Pharm's Kh/Gh kits, which measure in degrees per drop, not ppm per drop.


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