mold on wood aquarium cover

[schroeder]

If you don't use the Zinser specifically, you can use any outdoor grade product. Any kind of deck sealer should work. They all have UV resistance, and contain moldicide and fungiside.
I don't think it should be a problem if your hood is ventilated, but you may want to wait long enough for the canopy to completely dry (days as opposed to hours) for the volatiles to dissipate.