Ok - a few questions about GH. When we first set up our tank we checked the GH (and everything else) religiously (over 2 years ago now). We had to add HEAPS of this yellow stuff (can't remember what it's called) to increase the GH. After a while we were sick of having a yellow tank so stopped worrying about GH. Someone told us it didn't really matter. We've had pretty happy fish since and our water is quite soft.

So what's the go? What's the recommended GH for goldfish? What's the benefit of having the right GH? What can go wrong if we don't? And if it is important - can anyone suggest a product that increases GH which isn't yellow?

If your goldfish are happy don't worry about it

GH is a measure of calcium and/or magnesium in your water. As far as goldfish are concerned they can tolerate any level of GH. It's impact is minimal on goldfish whether it is very low or very high. Low GH or high GH will not cause any problems in your tank. (unless you keep invertebrates like snails) The only concern about GH is maintaing a consistent level. Just like any other water parameter, fluctuations of GH could be stressful to the fish (although if there was one I chose to lose control of it would be GH)

The more important measure for your tank is KH or carbonate hardness (sometimes referred to as alkalinity, or buffering capacity). KH testing measures the amount of carbonate ion in your tank. Carbonate is important because it buffers the pH of the aquarium. A tank with sufficent KH (4dKH or 70ppm) will effectively prevent the pH from changing rapidly and harming the fish.

Check out this link for a comprehensive discussion about KH, GH, and pH:

Click here

Crushed coral (calcium carbonate) or Epsom Salts (Magnesium Sulfate) will raise GH

thanks for that You've answered all my questions!!