DIY Sponge Filter...

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maxwell1295

Aquarium Advice FINatic
Joined
Jan 24, 2006
Messages
891
Location
Long Island, NY
I made a DIY sponge filter for my hospital/fry tank.

All you need is some PVC pipe, fittings, and cement, a large car wash sponge, an air pimp, and some airline. I also used a thermometer holder to prevent it it from floating. Others have used something to weigh it down, but I find the suction cup method to work just as well. Airstone is optional...I decided to use an airline shoved down the tube...


Here is everything you need (minus the airpump and airline):
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PVC cement:
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I cut the sponge in half and drilled a hole for for the PVC pipe:
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Here is what the PVC pipe and fittings look like fully assembled (prior to glueing):
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Completed sponge filter assembly...notice the hole drilled into the 45* piece for the airline:
img_626999_7_a38ad944e6e7811bddbe5dcfe70f4d9a.jpg


Here it is in action:
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very nicely done. And since it's just a cheap everyday sponge you can throw it away after each QT for that added level of sterile comfort :)
 
I put the airline down the tube, but it doesn't make the turn into the sponge area. Just deep enough to get the water moving in an upward direction...
 
I'm curious about drilling the sponge? How did you do that? Normal wood tools? Compress it first or not?
 
What keeps the fry from swimming down the 45 on top? couldn't you just cap it and drill a hole for the tube? And would the water just take the path of least resistance and come in the top instead of the sponge?

Does look good though, I love DIY.
 
spittinfly said:
What keeps the fry from swimming down the 45 on top?
Current. Just like any sponge filter. Anything strong enough to swim against that current isn't going to be hurt by it.
 
I thought you put a sponge filter on a line to keep fry from getting sucked up. So if the opening on top above the hose end is big enough for fry to swim down, and the end of the hose isn't plugged into the sponge couldn't the fry swim down the tube and get sucked up the hose? I got some fry and man are they curious.
 
spittinfly said:
I thought you put a sponge filter on a line to keep fry from getting sucked up.
There are two kinds of sponge filters. It sounds like you're describing a prefilter, that slips over the intake of a more powerful filter and prevents fry from getting sucked up. This is just a stand alone sponge filter. You stick an air line to the bottom of that tube, and the rising air creates a current of water going into the sponge, up the tube, and out the 45 degree elbow. There's no impeller for fry to get chopped up in.
 
I see, so that is an air pump line not a suction line. Very interesting. Looks like a great design and very easy to build/use. I will have to keep it in mind. Thanks for the clarification.
 
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