Hardness Testing

GH is the more important. KH is a measure of how easy the pH can change, so useful but not as important as KH.

Hardness - GH - affects fish more than pH so it is good to know your tap water's GH.


Have you used the tester yet? The hardness testers tend to cause confusion because you don't add x drops and compare the colour to a chart. You add drops until the liquid changes colour. And with soft water, the colour will never be bright because you reach the colour change after only a few drops. It is easier to see the colour change if after adding each drop and mixing it in, you take the lid off the tube, put it on something white and look down into the tube. That way you are looking through a couple of inches of water not half an inch and the colour appears more intense.




Edit to add - in your other post you mention living in the north west. I know that south Lancashire (OK, Merseyside  ) gets its water from United Utilities so I just typed in the postcode of my parents' old house to see if they give the KH on-line. They don't. Not many water companies do nowadays, unfortunately. And where they do, they call it alkalinity not KH. If you are with a different company, yours might possibly, just possibly, give it.

Have you used the tester yet? The hardness testers tend to cause confusion because you don't add x drops and compare the colour to a chart. You add drops until the liquid changes colour. And with soft water, the colour will never be bright because you reach the colour change after only a few drops. It is easier to see the colour change if after adding each drop and mixing it in, you take the lid off the tube, put it on something white and look down into the tube. That way you are looking through a couple of inches of water not half an inch and the colour appears more intense

Actually, another tip which I picked up from Sue and which has been invaluable to me is, when measuring GH or KH, to put 10ml (rather than 5ml, if that's the suggested amount) in the tube, then count the number of drips until the colour change, and divide by 2. This makes it much easier to work out, especially since it seems my levels are always midway between two points. [For example, in 10ml, it may take me 3 drips for KH to change, so I know it's actually 1.5; it may take me 7 drips for GH to change, so I know it's actually 3.5.]