hmm... that's weird. Are you making sure that no light is reaching into the tank and removing as much cyano as possible before blackout? I've also heard of people adding a cap of hydrogen peroxide/ 20 gallons everyday with the blackout. Other than imbalances with nutrients, I know that cyano doesn't appreciate strong water movement too. Could there be more flow added to the tank? david __________________________________ Do you Yahoo!? Win a $20,000 Career Makeover at Yahoo! HotJobs http://hotjobs.sweepstakes.yahoo.com/careermakeover ----------------------------------------------------------------------- -- 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