Can I make a suggestion? If the waterfall leaked, try using Great Stuff Pond Foam to seal it up. It is make for this exact purpose and is safe for fish once dry (24 hours) and does not need sealing etc.. It carves with a razor and is black. I have used it in countless tanks (installing backgrounds, mounting rocks, wood etc..) and find myself making excuses to use it again and again, it's actually fun stuff to play with . The pond looks great, I wish I could do an outdoor pond for my dovii pair. It gets too cold here in the winter months though.. Excellent choice of fauna BTW!