What if any is the difference in using mortor or concrete in constructing a pond? I am using a rubber liner and the sides of the pond are going to be river rock (softball sized) that i was planning on holing in place with mortor or concrete. Is one of them more desirable then the other? From what i know the only difference is the gravel in concrete, mortor is just cement and sand. Although i saw a post where someone recomended using mortor instead (which is what i used on my first pond) but they didn't mention why.

Also is there any long term effect on the pond water once the concrete has cured? With my last pond i always had problems with fish getting sick and slight ph variations, but i was also on a well and thought that may have to do with it.

Currently my plans are as follows to cure and setup my new pond.

Mortor in rocks and keep wet for a week, then let dry and clean with muratic acid, wash down and fill pond. After a month drain pond and clean with acid again and refill. At this time i will only put in goldfish. Then early next year (april/may) i will drian the pond and refill and replace the goldfish for a month and then replace with koi.

This should be enough time for all the lime/chemicals to release from the mortor/concrete from what i can tell. Any thoughts?