My pond is pretty small, maybe 500 gallons and nothing compared to some of the beautiful ones Ive seen on here. I just recently paid a "friend of a friend" to come fix my leaky waterfall. Now it leaks worse then before. He used a concrete mix between the 2 big rocks. They are huge and I can not lift them myself. I won't have him back to my house and he wants more money urgh!!! Is there a sealer I can pout over it or do I have to rip out the cement and put waterfall foam behind it? The water is seeping through the cement and going off to the side of the rock. Leaking where arrows are pointed. Thank you so much.