right now i have a 3ft kiddie pool that my duck and goose share. its gets pretty gross at the end of the day and i have to dump it each night (wastes a bunch of water). i was planning on getting them a 6 ft kiddie pool and digging it into the run at ground level. then when it was time to refill i could use the syphoning method with a hose. the problem is in the winter they wouldn't be able to swim because the pool would freeze. i also don't like how the kiddie pools are so shallow that they cant dive under and in stead its long and takes up lots of space. so now im starting to think about a large stock tank for them to use. i could buy one of those stock tank filters and heaters that twirl around and stuck up particles. the stock tanks seem like they would last way longer then a cheap kiddie pool. they are also deeper and don't take up s much room. what size would you recommend? im thinking 150-300 gallons so do you think a stock tank would work for them. and how often would i have to refill it if their was a filter?