No luck Jimbo, what worked for me was putting the rocks in a bucket with fresh saltwater and changing it every week. I think bound phosphates in the dry rock used for that tank were to blame. With the ULNS condition I was running on that tank they took some time to show up. Throughout the time battling the algae (and before) phosphates and nitrates were zeroish so I think the algae was using the phosphates as they were released from the rock. I think if the nitrates were higher in the tank before the algae was a problem bacteria could have more efficiently scavenged the released phosphates from the rock preventing the algae from getting a foothold.



