I read the document on tank setup here, very nice. I see on some peoples setups, that they have no ventilation. The entire top is covered by something, with a hole just big enough for the light.

I tried that on mine, i coated the entire top with aluminum tape, and left a hold perfectly sized for the light. Wife says that mold will build up with nowhere for the moisture to go, but i see other people do it on here.

Will mold build up? And is this a good way to insulate? I will add a layer of duct tape on top of it followed by another layer of foil.