05-30-2007, 02:33 PM
| || |
Hard water would be a GH of about 14, normally you want to keep it somewhere around 4-8. The numbers are not set in stone and many sources give different numbers but it all comes down to your fish as to what you want the numbers to be. Most fish are fine in a range of both KH and GH where certain ones will need harder or softer water.
You never want to see your KH below 3 because of the buffering capacity and I think the GH needs to stay around 3-5 to give the calcium and magnesium needed for good health. It has to do with something, the GH does, as far as osmotic pressure and swim blatters but I don't know the technical aspects of it.