What do you all use them for? Do you set up a mini pond in the backyard over the summer? Or is it for getting water ready to put in a tank?
I once put a kiddie pool in my backyard over the summer to grow out some fry. It was something like this
http://www.qualityinflatables.com/58431.html, which is like 200 gallons.
I used duckweed to protect it from the hottest sun, and bird netting from home depot to keep birds and critters out. I used it to grow out some fry for June-August. I used air powered sponge filters, and it kind of worked but I don't think it was ultimately worth the effort because I never did it again and I don't remember all that went wrong with it.