The gunite shell didn't leak, but the coping had begun to deteriorate. The cost of hiring a professional to plan and build the water garden was prohibitive, so I decided to do the work myself.  Searches on the web and members of our local pond club gave me enough ideas to get started. First, I needed to raise the bottom because I didn't want to have to filter so much water. It took about 42 cubic yards of pea gravel, or about 60 tons, to raise the shallow end to 1 1/2' and the deeper end to about 4'. 

(Pool: 16' x 32' x 8')