Quick Question - Gh To Kh Converter Anyone?

[Ami]

Hi

I've only got a GH test kit because I figured that this was more relevant for my fishkeeping than KH. However, the CO2 calculators seem to use KH only - does anyone know how to convert between the 2?

Cheers,
Ami

 

[@ombomb]

They're different things...

http/www.fishforums.net/index.php?showtopic=59467

 

[Ami]

They're different things...

http/www.fishforums.net/index.php?showtopic=59467

Oh ) I thought that KH was a measure of only the level of calcium but that GH was calcium plus magnesium etc. Therefore KH directly affects the alkalinity whereas GH doesn't, although there is a correlation between higher GH and alkalinity.

Think my lack of chemistry skills is showing!

I'm off to read the article!
)

Ami

 

[Ami]

Ok, read the article now.

KH is temporary hardness and GH is permanent. I test the GH, as I said before, because that's what I'm interested in for my tetras etc which all like soft water.

I now know that KH and GH are different, but because Wolf's article had that little table with what levels of KG and GH would mean soft water etc and there is a correlation between the two, presumably there is a way I can estimate my KH from the GH and vice versa? Any ideas guys?

Ami

 

[zig]

Not that i know of, you can estimate your KH from your ph but thats all it will be, an "estimate", it may not be accurate because of other unknown variables in your tank, you really need a testkit im afraid.

 

[Ptarmigan]

.

 

[Ami]

Errr, are you sure about that ? I understood GH to be General Hardness and is equivalent to total hardness (*)
and total hardness is made up of the permanent + temporary hardnesses.

So, to answer your original question, you could derive KH (bicarbonate/temporary) from GH by doing this :

Measure the GH of the water and call it reading A (this measures the permanent + temporary hardness)
Gently boil (simmer so as not to drive off too much water/steam) a sample of the water in a laboratory glass flask (**) for about 5 or 10 minutes then measure the GH after it has cooled down. Call this measurement B (this measures just the permanent hardness left over)

Subtract B from A and the difference will be the KH.

Purists would have you take 100ml (say), boil it for 20mins then allow to cool and bring the resultant volume back to 100ml by adding distilled water to it, before doing measurement B.

(*) Not to be confused with TDS, total dissolved solids
(**) You could try a stainless pan but I'm not sure if trace metal ions may contaminate the readings

PS
But I could be totally wrong because it is 1:15am local time and the only water chemistry worth considering at this time is the effect of a nice drop of malt whisky with or without a bit of spring water

Erm, no? But I guess I was half right! )

Will try your method suggestion tonight, as I can't get a KH test kit until the weekend. I really should get a master test instead of all these individual ones!


Thanks,
Ami