Yvan if you have a pH meter why dont you simply add a little bit of tap water. I have found using your pH meter simply add the desired amount of Tap and you can generaly arrive at a stable pH. I can't tell you a formula because everyones tap water is diffrent. Using your pH meter you'll have to figure it out for your self. You might try simply to add some tap water. BTW you must let it aeriate and sit for a few hours before your sure what pH youll have. Dave __________________________________________________ Do You Yahoo!? Send FREE video emails in Yahoo! Mail! http://promo.yahoo.com/videomail/ ------------------------------------------------------------------------- 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.