# How do you measure 0 KH?



## Symplicity (Oct 14, 2011)

I always wanted to ask. I am using my API GH/KH test kit and it says every drop is = 1 dkh. Therefor if it takes 4 drops to change colour your GH or KH would be 4.


NOW. How on earth do you measure a kH of 0 like some people post. lol

I cannot figure it out.... unless you do X-1.


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## randy (Jan 29, 2012)

If one drop changes colour, it could be anywhere between 0 and 1. So you let half of the water vaporize, test it again, if it's still 1 drop then you know your original KH was less than 0.5. Keep doing that until it's close enough to 0.

And yes, I'm just kidding... I normally say my KH is 0~1, I don't think it makes a big difference between 0 and 1 anyway.


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## getochkn (Jul 10, 2011)

Double the water you test with. If 1 drop still changes to yellow in 10ml, it's 0.


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## Symplicity (Oct 14, 2011)

getochkn said:


> Double the water you test with. If 1 drop still changes to yellow in 10ml, it's 0.


lol nice that works


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## getochkn (Jul 10, 2011)

Any of the test kits can be done with half water and half drops too. If it's 10 drops of solution A & B like for the nitrate test, use 2.5ml water and 5 drops of each to get the same result and make your test kit last twice as long.


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## Darkblade48 (Jan 28, 2008)

randy said:


> If one drop changes colour, it could be anywhere between 0 and 1. So you let *half of the water vaporize*, test it again, if it's still 1 drop then you know your original KH was less than 0.5. Keep doing that until it's close enough to 0.


If you let half the water evaporate, the carbonate hardness will remain the same 

The other methods posted work to measure a kH less than 1, as the kH test kit works by titration.


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## randy (Jan 29, 2012)

Darkblade48 said:


> If you let half the water evaporate, the carbonate hardness will remain the same


I guess I figured out the flaw in my theory but I was really just joking.


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