Hi Deva and FML -- I have a filter (and little spray fountain) to keep the water clean -- waaay overkill in strength, since what I have now for a ferret swimming pool is a big plastic storage box to be sunk into the ground. Anyone know anything about pumps? This one is for up to 500 gals, I think, and the container might hold 15 - 20. Would the pump burn out? Cause a whirlpool in the smallish container? Fsh in a larger pool sounds so cool! Would the ferrets eat them? I suppose some of them would eat some. I wonder if I can get the nearest city to supply them to me.If not, dos anyone know what is available commercially? I wonder if the ferts would chew this storage box -- it is made of the common clear/translucent plastic, and I will leave the rim and an inch or two above ground to reduce ground spill. Let's see, a storage container with whirling water and churning fish and ferrets. I guess some rethinking could be needed here. Also, I am still thinking about the water tank -- in fact I have paid the $s but haven't yet picked it up. Can anyone think of a reason this would not be a good idea, especially if I can't get the thing sunk into the ground?? I expect I need to get lots of small holes punched into it at the same time as when I get the top cut off. I hate using plastic, but since its purpose is to hold water, I assume it is pretty safe. I plan to fill it with dirt except for the last 4 feet, and I have shade cloth for 1/2 of the top. [f-c] [Posted in FML issue 4950]