I changed some lighting recently and have experienced a green water bloom. I don't know whether the change has provided too much light, too little or just the wrong spectrum.

The tank is a 180G with four bulbs. There were four 6' VHO bulbs, but I swapped out two of these for 5' T5 HO bulbs (Icecap ballasts). I could certainly switch back, but until I understand what is going on I feel that I would be making an uninformed decision.

Thoughts? Thanks to any that post.