Dont know that this qualifies as a tank but I put a pond in my yard last year. I used a 350 gallon galvanized cattle trough for the main body. Just dug an area large enough to sink it partially into the ground. Looking forward to spring this year when I can stock it with tadpoles, some fish and more plants.

Nice way to fix a pond. I too have a pool outside and am hopefully going to get to dig it up in the spring and move it so it will be easier to take care of and I want to fix it with the rock around it to make it look more natural.

I didn't have to worry about putting tadpoles in it, they came on their own, the frogs love my pool. Everything from little tiny ones to the big bull frogs. Would like to keep the big ones out cause they are death on baby fish.

Pa, you may not get away with getting tadpoles in there. Tadpoles are extremely sensitive to metals, so the trough may kill them... Be careful what kinds of fish you stock it with. Koi would definately grow too big for that pond, so look for goldfish (smaller ones, large 'feeder' goldfish, may be better than big goldfish, as they grow fast) or other coldwater fish.

What a great idea PA, thanks for sharing. MM