Constructing a 'pot filter' --- a good thing to know.

[Sk8r]

Any submersible plastic container can become a filter.
You need: a little bit of plastic lighting grid, commonly called eggcrate: [Lowe's lighting dept]
A small pump with appropriate hose for the 'out' line.
Pillow floss: cheaper than filter floss. Fabric store. You can also wrap it around a bit of carbon.
1. Put the pump in the bottom of the container with the hose sticking all the way up to the top.
2. Use eggcrate atop the pump to prevent it winding floss around its impeller: put the intake shield on it, if you have one.
3. add a big wad of floss
4. more eggcrate atop that. Weight the eggcrate with a rock or glass object that you can attest is clean of stuff that might dissolve.
Run the pump, change the floss at need: don't try to set it up biologically. Your purpose is removing crud or supporting a fish in qt.

I've used these on microscale for hospital/qt; and used them in a 5 gallon bucket in my koi pond. They're good if you have to leave a pond for a week in someone's hands and you're afraid the regular filters will clog. This thing will actually get more efficient (up to a point) the dirtier the floss gets.

Beware, however, of leaving it unchanged in a marine tank: you don't want it going biologically active, because it'll raise nitrates if it does. But for removing a sand kickup or powering a qt, it's a help.