can i usr roof tar for pond sealer in between two sheets of plastic?
I wouldn't recommend roof tar. Roof tar is made for water that is running off quickly not water that's going to be standing in place for a long time. I'd recommend getting a sealer like the first person stated.
Don't use plastic. It will crack over time. My first attempt years ago was with a swimming pool liner. The part not in the water cracked and spread below the waterline. I also suspect that the roofing cement will react with the plastic. Even if it didn't melt the plastic, one small tear in the top layer would be toxic to fish. Go with the rubber liner designed for fish ponds. The cheap way will cause you nothing but grief. Don't forget a pump and filter. Yahoo fish ponds or garden ponds. It will give you plenty of design ideas. If money is an issue, consider a blue childs wading pool.
No. If it contacts the water it will contaminate it and possibly kill everything you plan to put into the pond. They make a sealant for pond liners I suggest you use it instead.
