by Mike Wise » Sun Nov 16, 2008 10:17 pm
In theory, rainwater has no or almost no hardness. Therefore if you mix your tap water 50/50 with rainwater you will decrease the KH by half or to around 95 ppm. For most apistos, this is sufficient for breeding purposes. For those from truly blackwater biotopes, you will need to get it to about half of this (<50 ppm/3°dKH). It should be easy to lower the pH to below 5.5 with peat and probably below 6.0 with oak/beach leaves. The trick is to keep the pH from dropping too low, too fast. I prefer to mix my peat filtered water with tap water at the proper ratio in a separate vat & check the pH before adding it to the aquarium with each water change. The only way to keep the hardness low is to replace water from water changes with a mixture of tap & rainwater of the correct ratio. I have naturally soft water (<50µS/cm; roughly 25 ppm), but I filter water through sphagnum peat to lower the hardness and pH for some of my very picky apistos. You can use any method that pumps water through the peat. Just check to make sure it is not too acid before adding it to your tank.◄