For anyone thinking of pool filter sand as a substrate, I would suggest testing each purchase (all batches even within one brand can be from different sources) for it's ability to release alkalinity/hardness into the water. A lot of the sands are better suited to Rift Lake aquaria. Martha ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@listbox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@listbox.com.