what device is this and what does it do?

[GTO]

I feel stupid for asking but what is this?

 

[Mgamer20o0]

its a sponge filter

 

[Ghost_knife]

It's a older form of filtration, like Mgamer said. It's a sponge filter, a Vouge of days past. least they dont sell them here. Good for breeding tanks and fish that are tiny

 

[Mgamer20o0]

i also fine it nice to keep on the intake of my fluval filter. it keeps the plants out of my filter.

 

[Rallysman]

I think they are one of the most under-rated forms of biological filtration. I'm setting a 110 up with nothing but sponge filters. If hooked to a good air pump they are great filters. Also, as mentioned before, they are priceless in breeder tanks.

 

[aardvark1]

Yep, a sponge filter.

Use one in my shrimp tank; no chance for the shrimps to get sucked up into filter.

Works great, side bonus, shrimps like to graze on the stuff collected on the sponge...

 

[wataugachicken]

i use them as stands for powerheads. very handy. when it gets dirty just squeeze out in a bucket of old tank water until it's clean again.

 

[Rallysman]

They're also great to keep in other well filtered tanks to use in case of emergency.
With an established sponge filter you can start a tank up very quickly if needed.

 

[cohazard]

They're also great to keep in other well filtered tanks to use in case of emergency.
With an established sponge filter you can start a tank up very quickly if needed.

That's my favorite use for them!