Some Notes on Laterite.

Laterite shouldn't effect your GH, KH or PH but it could raise the iron levels considerably if it is used wrong. The best way to use it is to put a thin layer, maybe 1/4 to 1/2 inch on the very bottom of the tank & then to cover it with 2 1/2 - 3 inches of sand or fine gravel. This traps the laterite underneath the gravel & limits how much iron it can leach into the water column, if it leaches any at all. If you use gravel over laterite you should make sure that the grain size of the gravel is under 4mm or the laterite can still leach through the large spaces in between particles. Be aware that once you have planted a tank with laterite in it, it is not a good idea to move your plants about. Moving plants in a tank containing laterite can very quickly make your tank look like you have filled it with coffee.