Over the years I have had a several different fish tanks. As a plumber, I would put any type of mechanical fittings or valves into a tank as habitat.
Always having aggressive fish, a ball valve provided great refuge to small fish. Also, a real mean fish will go after its reflection when there is no food.
Step 1: Materials &Tools
You need a ball valve and a Crescent wrench. * This instructable is on one type of ball valve. The only difference to the other style ball valve is, you put it in a vice and and turn it open with a pipe wrench.*
Step 2: Break Down
With the Crescent, remove all the nuts including the packing nut under the handle.
Step 3: The Guts
Remove the handle, bolts, O-ring, and Teflon seal.
Step 4: Position Ball
With the Crescent, position the valve stem to the closed position, so the slot will let the ball roll out.
Step 5: Finished Product
In this photo, I have the ball sitting on the packing nut. Normally the ball just sits in the gravel. This ball valve is also 1 1/4 but several feeders will fit into a 3/4 in full-port ball valve.