Green BTA is not green??

[nanmer]

I have three green BTA, at least they were when I bought them. I have PC lights that I supplement with MH. I feed them prawn pieces and many other goodies and they have huge appetites. They are growing like crazy. The problem is I would like them to be green and not the red/brown color they are at present. Is it a lighting thing or is there magical green fairy dust I must sprinkle at midnight???