A homemade filter for tiny tanks

written by: Matt Lichter

This is a small zeolite filter I've used in tiny, temporary tanks. Right now I'm using it in a 2 gallon tadpole tank, stocked with a few tiny tads. I wanted some type of filtration, but didn't have the time or energy to go through the cycling process before introducing the tads. I figured I would just use zeolite, since for the short term that seemed easiest to me. Since it was such a tiny tank, I was also looking for something cheap -i.e. DIY.

1. Find a small plastic container such as a film canister, prescription container, empty fish-food container, or any other small plastic container that isn't contaminated with detergents or other harmful substances (i.e. no shampoo bottles). Rinse well with tap water. (Film canisters may contain trace heavy metals, so add some tap water conditioner in the rinse, one that says "detoxifies heavy metals".)

2. Find about 3 to 6 inches of 1/2-inch tubing. This could be from the pet store or polyethylene tubing from the hardware store. Cut a notch the bottom end (see figure), or cut it at an angle. This ensures good water flow.

3. Cut a hole slightly smaller than 1/2 inch in the lid so that the 1/2-inch tubing makes a snug fit. Put the lid on the container and push the 1/2-inch tube all the way down to the bottom of the container. With a heated nail or a drill, make a bunch of small holes in the remaining area of the lid.

4. With a heated screwdriver or a drill, make a hole in the side of the 1/2-inch tubing for the airline tubing to fit. Again, the hole should be slightly undersized for a tight fit. It would probably help to make the hole at an angle, since the airline will be coming in at an angle. Also, when making the hole, it is good to leave yourself some room (1/2 inch) between the top of the lid and the bottom of the hole. This will make the canister easier to fill with media later on.

5. Press the airline tubing into the new hole, and push it about halfway down into the canister. You don't want air bubbles to find themselves going back through the media the wrong way.

6. Now, unsnap the lid and swivel it out of the way, as you keep the 1/2-inch tubing all the way down to the bottom. Fill the rest of the container with zeolite or the media of your choice. You should be able to get a few tablespoons of media into a film canister. Carefully snap the lid back on and hook the airline tubing to a small air pump.

The whole thing costs practically nothing beyond the media and the air pump. If you have a few tanks you probably already have all the materials laying around.