DWC Resevoir Cover???

So I have a small 1 gallon res I purchased on eBay, the res cover comes with 6 wholes for net pots, I only wanted to use one slot, What can I use to cover the other 5 wholes?

now I've had this same thing before but I just covered the wholes with Mylar tapped to the res but I noticed like a salt build up or some kinda of mold like shit, coming from underneath the tape, so is putting tape on top a bad idea??

It's really not that hard to solve... be creative. You could super glue pretty much anything that's opaque and unporous to cover the holes. Try aluminum foil.

I just don't want any salt build up or mold

foil tape would be fine, or pvc tape. Anything light proof that'll stick.