can it be done? this summer i would like to make a big outdoor pond, but with the size i want to make it, buying a liner would be crazy expensive. i was looking on ebay and found some pool liners that arent a bad price, but im wondering if they would be any good, and mainly, do you guys thing their fish safe? this is the kind of liner im referring too, http://cgi.ebay.com/12x20-Blue-Abov...210?pt=LH_DefaultDomain_0&hash=item5197a0323a