DSB and light in stand

[cdalmost]

When I built my stand I decided not to include a solid wood topper, partly to save on the cost of the plywood and partly because it is structurally unnecessary (just look at the wrought iron skeleton stands). I'm running an algae scrubber inside my stand and the light spillover is allowing what appears to be green cyanobacteria to grow underneath my sandbed. (You see this happening on the sides of DSBs sometimes when the aquarium is in a bright enough room.) My question is, is this bad?

In theory, as I understand it, DSBs are supposed to offer a low oxygen zone where bacteria that can convert nitrate to nitrogen can thrive. If this is the case then it would seem that my situation is very bad (or at least contrary to the point of having a DSB), because the green slime will be pumping out oxygen whenever the AS is on. Thoughts?

 

[elegance coral]

If it is cyanobacteria, it's also fixing nitrogen. In other words, it's taking N2 and causing it to become more NO3.

 

[cdalmost]

So, you think that's making it even worse?

I'm trying to decide whether to go in the stand and cover the bottom of the tank with something opaque. I tested my nitrates the other day and they read 0 ppm, but it was just a cheap kit.

 

[JohnnyRI]

I would block the light if possible. I have seen that but i would be nervous about it. I worry all the time about my tank though