replace light bulb induces cynobaterica??

[Navarchus]

Look there are now two identical tanks!
Every tank will react in different manner to changes.
You should understand the principles of this delicate biotope and how it works.

I would say that there is a built-in paradox in our hobby. On one hand we say that one of the most important keys for successes is stability! On the other hand the one thing that you don’t have in your system in stability, since the aquarium always in change, coral grow, Carolina alga spreads, fish and corals in your system consume different elements and minerals that can change you water chemistry and so one…

In your tank you made two major changes in a short period of time, one is rock changing and the other is introducing new bulbs to your tank. In is never a good idea to make multiple changes in the aquarium in a short period of time.

One time I have changed light system and skimmer (into stronger ones) in the same week cussing a total bleaching in my system.

Last buy not least …I believe that cutting back light and siphoning out the cyano will do the trick.