[Khledar]

Well the whole concept of the bong is to use evapouration to cool; this is done effectively by increasing the surface area between the water droplets to the air, so that it can occur at a decent rate. I think by using sponges it would definately slow the rate at which the water falls, thus increaseing the window of opportunity in which the water has the chance to evapourate; however, by using sponges, I think, besides the horrible smell your evapouration rate would be quite poor. Why, simply because the sponges by soaking up the water will not allow the water to evapourate into the surrounding air. The sponge would become full of water, and even if it wasn't "full" it would restrict the air too much. Let me try to explain a bit differently what I think would occur. The shower head splits up the water into many particles, but I think the sponge would almost regroup the water into streams rather than teeny-tiny droplets which have a high surface area.

My .02.

GL with the bong though!