I think the 1hr on / 1hr off is more to prevent UV shock / light burn to corals who are "tuned" to a certain amount of energy coming in at them.

The tank's adjustment is going to take a little while. But it will adjust. And yeah, the usual recommendations about cyano will help ... skimming, excess nutrient management, water flow, etc.

After some consideration about then, and now - I am definitely increasing my rock. :mrgreen:

The hr on hr off thing was mainly for the couple of zoos and star polyps I have. The newer corals I expect had already been under constant MH for a while so they have not gone through the same acclimatisation.

They appear ok though.