I got a hardness test, now what's it mean?

[Vyache]

I have some discus and want to provide them with the proper water conditions. I just bought a KH/GH test kit made by Hagen. I tested my water and its got a GH of 60 mg/L (ppm) CaCO3 and a KH of 40 mg/L (ppm) CaCO3. My pH is 6.6. I used a discus buffer product to lower the pH a bit and have DIY CO2 in the tank as well. My tap water has a 7.4 pH. I've got a discus book and its recomendations are in units other than that which my test provides. Its got a little conversion chart but its still not exactly what the book has.
Can anyone tell me about water hardness? Whats the difference between KH and GH and which is important to discus fish? The little booklet that came with the test says that my KH is too low but I think that the test is used mostly by saltwater aquarists. If I have a KH that is too low do I risk acid fall? I've got some idea about whats going on here but just need a little straightening out.
Thanks
-Vyache

[RedTurquoise]

Temporary hardness is sometimes referred to as carbonate hardness (KH) or acid binding capacity (ABC), and is easily removed by boiling. Boiling takes out bicarbonates of calcium and magnesium, which are soluble in water, by precipitation. It is this which in hard water areas creates a white scale in the kettle.

The fraction of total hardness which cannot be removed by boiling is called permanent hardness. Permanent hardness can therefore be determined by subtracting the figure for temporary hardness from the figure of total hardness.

Carbonate hardness (KH) may often be greater than total hardness (GH) because of the presence of sodium and potassium in addition to calcium and magnesium. These elements do not increase hardness but occur along with bicarbonate anions to increase the quantity of bicarbonates.

Imo, less breeding, hardness isnt that important. Constant parameters are the most important. I know that most books mention adding this and that however I do not agree along with most hobbyests and breeder. In actual fact, most breeders grow out juvs in harder water and higher ph. If you do start messing with parameters, you will find that it is difficult to match parameters each and every time. I have tried and have crashed my ph often, having to start over again (in a holding barrel, never in my tank).

Your hardness is good, its even softer than my tap water which is 100ppm both kh and gh! Hope that helps!

[Vyache]

I was plesently supprised when I found I had soft tap water. Thats one of the things that made me unsure if I was reading the test right. I'm glad I don't have to do much in the way of adding chemicals.

[RedTurquoise]

<<Im jealous>>