You can mortar them to the liner and to each other. I would use mortar
since it is made with sand, where concrete has rocks in it that makes the
minimum thickness nearly 1 inch. Try to keep any of it out of the pond
while you are working. It is very alkaline, with a pH of about 13. If you
can keep it above water level, then it should not cause any problems, but if
it is below water level, the lime that is one of the byproducts of the
chemical reaction, will continue to leach into the pond, causing high pH
values. It really needs to cure for several weeks and be allowed to air dry
before submerging in pond water to limit the leaching of the lime.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"Black Knight" wrote in message
...
I plan on putting several cources of flagstone in and around my pond,
the question that I have is , should I cement in the first cource with
type 1-a concrete or not? I was planning on doing this for the rest of
the layers but I'm not sure about the rest?
Any advice out there?