I have used DH for discus, angles, and apistos (Apistogrammoides love half DH and half city water) to no ill effect. My DH does NOT have copper coils though. I save the water in plastic garbage cans throughout the summer. Have three filled now. I also leave bogwood I am not using in there to soak and stay heavy. Here's an amazing thing... some duckweed go into one of the cans but still grew despite a cover on it. Go figure! It didn't reproduce, but stayed green! ------------------------------------------------------------------------- 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. apisto-digest@listbox.com also available. Web archives at http://lists.thekrib.com/apisto Trading at http://blox.dropship.org/mailman/listinfo/apisto_trader