Tin foil NFT rockwool

Hey guys, to prevent algea from starting up on my rock wool cubes, I have cut out tin foil squares, cut a line half way down with a small square / area for stem, folded the foil over my rockwool cubes under the corex.

I believe algea starts up on the cubes etc after a while if not covered up, does this sound ok? I'm in the process with seedlings under a cfl just now, so any advice would be cool, or a slap if am doing this wrong!

Nobody tell me whether this is a good move or not?

Yeah that will work. Anything to block the light from hitting the rockwool.