Making DIY sponge filters

[Freezekougra]

Yes, I know they're cheap

1) How do I drill a 3/4" or 1" hole if all I have is a small screw bit? Could I just stab it with a screw driver and tear apart a hole?

2)If I make a 4x4x4 sponge, how heavy will the weight need to be to keep it from floating?

3)Anybody know any good sources for open-celled foam? What kind of stores carry them?

Thanks

 

[lojik]

1) Buy a correctly sized drill bit. Freeze the foam block in water and drill the hole through the frozen block.

 

[Bobbys]

I've successfully popped out holes for sponge filters using 1/2" or 3/4" wide length of copper tubing, and sort of sharpened or filed 1 end an just twisted the pipe into the foam to make a clean hole.

www.engineeredfoam.com

http://www.swisstropicals.com/Poret%20Filter%20Foam.html
US supplier of foam. Somewhat expensive.

and

http://www.janrigter.nl/mattenfilter/ for theory.