Blasto lighting

[outtafocus]

I recently picked up a nice little rock with some bright green and red blastos on it.

I know that blastos dont really like direct MH light so I have them placed off to one side slightly hiding under a rocky over hang. They arent fully shaded nor are they getting full light.
They havent really opened up very well in this tank. I have experimented with placing a dark piece of plastic to block a large amount of light and letting them get full light from this area.

My question is, how do I know if its too much light they are getting or too little?

They are also not in any direct flow because I have read they dont like too much flow.