making a sponge not float

[andreahp]

I was interested in making a simple sponge filter to be run in my main tank and used for QT purposes. I assembled it last night and tried submerging it - I'm assuming I'm supposed to cover it with gravel in order to get it to stay on the bottom? Is there anything else I can do besides that? I wanted to get the new filter ready so I can set up the QT with dechlorinated water and have a filter all ready - my main tank is 46gal - QT tank is 10. I bought a utility sponge from Home Depot and cut it in half - is it too big? Should I make it thinner?

 

[BigJim]

Attach a lead fishing weight to it. It's cheap and lead doesn't dissolve in water so it's safe.