Krylon is fine. Just wipe the back down with rubbing alcohol, let dry and use light coats. Watch for drips so go nice and easy, make sure to tape up everything and cover the top. Nice a steady here will win the race. Many light coats...
"When creating an aqua scape, strive for the beauty of imperfection, as its art and there is no wrong or right, it's left open for interpretation" James Findley