Why are sponge filters wide and not tall?

[Brett]

So, I know the basics of how a sponge filter works. Bubbles lift the water, create a vacuum, and draw water through the sponge to fill it. My question is, why are larger sponge filters always WIDER? Would it work to make one taller instead? Stack two or three sponges, and elongate the inner section? That way you could have a larger filter, but not take up more of a footprint in the tank.

Hope that makes sense, and thanks for the advice!

[Zac]

If I had to guess it’s probably because there’s more thickness to the sponge so more stuff can get trapped and stuck deep in the sponge before cleaning. If you had a taller one with a less thick sponge, you would probably have to clean it more because the sponge is thinner. That’s just my guess though.

[HH Morant]

Only so much water is pushed up the lift tube. A taller sponge filter means a lower flow rate through the sponge. 

That's my guess.

[JettsPapa]

In addition to what was mentioned above, I suspect that since the air comes out of the line at the top of the filter, most of the water coming in would also be at the top of the filter if the filters were much taller, so the lower portion wouldn't be doing anything.

[Flumpweesel]

I think you can stack them if you switch to a powerhead

[Biotope Biologist]

It's a combination of maximizing flow rate and surface area. They take up a large footprint by design, because we in this hobby are slaves to our bacteria overlords.