I have done that for years. With no ill effects. It has many benefits: creates blackwater, lowers hardness and great place for infusoria to grow. Just keep boiling it and you should be fine. Davidde ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@majordomo.pobox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@majordomo.pobox.com. Search http://altavista.digital.com for "Apistogramma Mailing List Archives"!