Looking for advice in using Drylok on a koi pond. I have a koi pond constructed with poured concrete bottom and wall block for the sides. The bottom and the sides have been rendered with mortar. I am looking for a paint/epoxy of some sort to protect the fish from the cement. The pond at this point holds water perfectly fine. I have been soaking it for about a month with pool acid. I still do not feel safe about the lime in the cement and would like to paint it further. Herco rubber is too expensive as there is about 1200sq ft of surface area. Is Drylok a good option? Please help.