Sponge filter?

Dec 20, 2006
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Michigan
Ok, so I went to my lfs today and bought a sponge filter for my fry tank, and I have a few questions. First of all, how in the world do you keep it anchored to the bottom? Mine keeps floating up! I suppose this next question might answer the previous for me, but maybe not... Is the sponge part of the filter suppose to sit on top of the gravel, under it completely, or just be surrounded on the sides by my gravel? And... lastly, this isn't what I expected it to be. How does it actually work, since virtually, all it is is a sponge with an air tube/stone sticking out for aeration... I'd like to know how it filters the waste... Thank you.
 
My sponge filters are weighted, so they don't float....squeeze the sponge to make sure all the air is out of it...without knowing what kind you have, it's a little hard to say....here is a site that expains how they work and how to maintain them...

http://ezinearticles.com/?The-Proper-Care-of-Aquarium-Sponge-Media&id=397980

They work well for fry tanks or tanks with low to moderate bioloads...if you have higher bioloads, just add more sponge filters to the tank....
 
The air displaced in the tube draws water through in its place. Its a very weak vaccuum. If you squeeze it enough it will sink. They dont need to be under gravel at all because the bacteria is housed in the sponge itself.
 
Hmm. Well, mine has no air left in it, but about every 10 minutes it floats up... If that link doesn't help, I don't know what I'll do!
 
Yep, that article didn't help and I still can't keep the sponge down.
 
Ah.. ok, I'll try that...
 
i have never had a sponge filter, but ive seen them in my LFS. do you attach a water pump to them or an air pump?
 
i have never had a sponge filter, but ive seen them in my LFS. do you attach a water pump to them or an air pump?

Either. You can have a powerhead pull water through them or have an air pumps which create a small vacuum.

Personally I think they are one of the most underrated filters. I have a 110 that was filtered with nothing but 2 sponge filters and a powerful air pump (which also ran several other sponge filters)
 
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