Have I done this correctly?

[MattW]

I don't have much knowledge and or experience in water chemistry. I'm trying to find the GH of my tank so bought a test kit. This is the first time I've ever tested the GH and KH of my water. My local water company tests in Hardness Clark as seen in the image below. The Test kit I have does KH in ppm and GH in mg/L. So I converted it into hardness Clark with an online calculator to make an easier comparison. Have I done this correctly?

(Results from Tests KH - 71.2 ppm / GH - 106.8 mg/L)

WATER FROM TAP

TANK WATER

(Test kit used)

Aquarium Test Kit - Hardness Test from NT Labs

KH, also known as “total alkalinity” or “carbonate hardness”, is a measure of the buffering capacity of the water in your aquarium. General Hardness is a measure of the total amount of minerals dissolved in the water.

www.ntlabs.co.uk

 

[Ichthys]

ppm and mg/l are the same. 71.2 and 106.8 are 5 and 7.5 Clarke, or 4 and 6 German. We usually call it in German, so your KH is 4 and GH is 6.
(17.848 ppm is 1 German).

 

[MattW]

ppm and mg/l are the same. 71.2 and 106.8 are 5 and 7.5 Clarke, or 4 and 6 German. We usually call it in German, so your KH is 4 and GH is 6.
17.848 ppm is 1 German.

Thanks for clearing that up! I now see why I didn't pass chemistry

 

[Ichthys]

Thanks for clearing that up! I now see why I didn't pass chemistry

I didn’t do great either, but I passed Fish.

 

[Essjay]

GH is worse than litres/US gallons/Imperial gallons for volume. There's a whole host of units but fish keeping uses just two of them. And some units are so close to another that they can be regarded as the same.

mg/l calcium carbonate and ppm are the same.
mg/litre calcium is a favourite of some UK water companies
mg/l calcium oxide occurs occasionally with UK water companies.
German degrees is the same as dH or dGH
French degrees
Clarke or English degrees (same unit, different names)
Grains per gallon, used in the US which is almost the same as dH/German degrees, just a tad different.
Then there are also mmol/litre and mval/litre which I've only read about and never seen in use.

The units mg/l calcium carbonate and calcium and calcium oxide are not actually the amount of those substances, they are what the number would be if all the minerals which make up hardness were those substances. I do have an ancient degree in chemistry but my younger son has a doctorate in chemistry and used to work as analyst for a water testing company and he explained all that


Fish keeping used ppm/mg/l calcium carbonate and dH/German degrees.