That's what I figured, we pay $250 for a five gallon bucket of their industrial stuff.
Did you ever think about using UGK Drylok? It says its for fish ponds......
wow this is turning out really nice!
i like the piece of driftwood a lot too.
copper safe as in chelated copper sulfate?
many may advise against that as chelated copper may stay with the wood.
this may render the tank unsafe for some invertebrates.
use of chlorine or hydrogen peroxide would prob be safer.