koi destroy everything when they get bored .I bought some of those giant christmas ornaments and plug up the one end where the hook was and they love to push them around the water ,better than destroying my lilies.I bought the tanks at a house auction and got them dirt cheap .I check out auction zip.com all the time to see where auctions are and see if there is anything good .Got a whole box pond supplies last year at auction with a big 45 mil thick liner in it that was 20x30 and a couple of pumps and fittings and other stuff for 25 dollars