Homemade sponge filter

We were talking about air pump driven sponge filter in another thread. It seems many bros swear by it. Frankly, I can’t believe such a low-tech device will work for our heavy waste-producing goldfish. But repeatedly I was asked to try it out.

Well, I can't find one as big as I want... so I made one instead.

Cool boh?

Please tell me how you feel about this unorthodox setup.

I figure that the waste will remain in the tank?

Originally posted by happybuddha
We were talking about air pump driven sponge filter in another thread. It seems many bros swear by it. Frankly, I can’t believe such a low-tech device will work for our heavy waste-producing goldfish. But repeatedly I was asked to try it out.

Well, I can't find one as big as I want... so I made one instead.

Cool boh?

Please tell me how you feel about this unorthodox setup.

Very innovative thanks for sharing.

when u wanna wash the filter i believe most of the shit will still go back into the tank

u might wanna have a look at something i have tried and it works
and cheap



just wrap the wool round the straw and then can liao
can use rubber band or something else to hold it in place
then add the air tube to the left of the straw
but be sure to seal well the part where the tube enters the straw area well
a bigger version can be done
using the same concept


hope u dun mind me hijacking ur tread

Originally posted by happybuddha
We were talking about air pump driven sponge filter in another thread. It seems many bros swear by it. Frankly, I can’t believe such a low-tech device will work for our heavy waste-producing goldfish. But repeatedly I was asked to try it out.

Well, I can't find one as big as I want... so I made one instead.

Cool boh?

Please tell me how you feel about this unorthodox setup.

careful... all your bb is in that filter.. once you do a through wash part of the bb is gone..

Originally posted by happybuddha
We were talking about air pump driven sponge filter in another thread. It seems many bros swear by it. Frankly, I can’t believe such a low-tech device will work for our heavy waste-producing goldfish. But repeatedly I was asked to try it out.

Well, I can't find one as big as I want... so I made one instead.

Cool boh?

Please tell me how you feel about this unorthodox setup.

I can see 2 disadvantages with this design.

a) Everything that sink to the bottom of the tank will be stuck in the sponge and this includes fish food. The idea of sponge filter discussed here is the sponge is a good biological filter ie. removing the dissolved, unseen ammonia and nitrite but not the solid waste.

b) The location of the air lift tube is toward one side and at one corner. Unless the air lift tube can generate a strong suction with just aeration, there will be many death spots at the far end. For a standard round sponge filter, the flow will be more consistent.

Cost wise, I think the cost of your innovative design will be the same as a standard sponge filter.

Originally posted by Kawai
I figure that the waste will remain in the tank?

Yeah man, all kinds of waste will remain visible in the tank. I’ve removed the ranchu and let the tank cycle with some rotten bloodworms and some left-over lionhead pellets.

It’s not a pretty sight. But that’s one of the disadvantage of a sponge filter – visible waste. Sigh. Oh well, I suppose rotten bloodworms are better than poo poos which we know our goldfish will nib on. Ok, that’s stupid but it happens. Thus visible waste is a big no-no.

I guess I have to siphon out all the wastes on a daily basis. I’ll do that after cycling the tank.

Originally posted by gabriel06
when u wanna wash the filter i believe most of the shit will still go back into the tank

u might wanna have a look at something i have tried and it works
and cheap

just wrap the wool round the straw and then can liao
can use rubber band or something else to hold it in place
then add the air tube to the left of the straw
but be sure to seal well the part where the tube enters the straw area well
a bigger version can be done
using the same concept


hope u dun mind me hijacking ur tread

I plan to move the fishes out when I clean the tank. Then squeeze the sponge to dislodge trapped wastes. After that, drain all the dirty water away.

Otherwise most of the waste will go back into the tank. I guess that’s the second disadvantage of a sponge-based filter – tougher maintenance.

Thanks for sharing your own DIY method and I appreciate the diagram too. The “straw” is housed within the sponge? I thot of using my spare rainbar and punch it through the middle of a big fat cylindrical sponge. But since I want the filter to occupy as little swimming area as possible, I need it to lay flat on the ground. I thus figured a standard UGF actually works nicely. The UGF filter is trapped underneath the sponge and it draws water down and through the sponge.

Hijack? Nah, you're participating, but hijacking.

Originally posted by bearbond
careful... all your bb is in that filter.. once you do a through wash part of the bb is gone..

Hello my favorite DIY man.

My experience with other filter system shows BB can re-populate quickly. Take my Eheim AquaBall for instance. I clean the sponge once every 3 days as unicellular algae clog it very quickly. I thoroughly squeeze every drop of waste out until the sponge is absolutely free of any trapped waste. The remaining BB go back into action without any noticeable decrease in performance. Amazing. But if I clean the sponge using chlorinated tap water it will be a different story entirely.

In this light, I actually prefer a sponge to sinter glass or ceramic media. The later two are difficult to clean and refresh. One up for sponge-based filter! But sinter glass and ceramic have far more effective surface area to cultivate BB than a sponge. They’re actually dirt-cheap too.

Originally posted by goldfishfever
I can see 2 disadvantages with this design.

a) Everything that sink to the bottom of the tank will be stuck in the sponge and this includes fish food. The idea of sponge filter discussed here is the sponge is a good biological filter ie. removing the dissolved, unseen ammonia and nitrite but not the solid waste.

b) The location of the air lift tube is toward one side and at one corner. Unless the air lift tube can generate a strong suction with just aeration, there will be many death spots at the far end. For a standard round sponge filter, the flow will be more consistent.

Cost wise, I think the cost of your innovative design will be the same as a standard sponge filter.

Wow, excellent feedback!

(1) You’re absolutely right on this. Pellets won’t get stuck due to their size and the relatively week suction providing by the air-driven flow. But I overlooked bloodworms which are small and light! In this sense, this sponge gravel bed filter acts like mechanical and biological filter while the usual cylindrical sponge is more a bio filter. I completely overlooked this important point.

(2) I could put another air-lift tube at the other corner… but I figured since they have designed this UGF with just one, it should be okay. The sponge will clog up gradually. There’s no doubt that standard round sponge will provide a more consistent flow but it can’t beat the gravel bed sponge for sheer size of effective surface area.

The cost of the UGF is $2, while that 1 1/2 thick, 1 feet by 6 inches area sponge cost $5.

[side-track] Are you the one looking for “A complete guide to fancy goldfish” book by Dr Erik Johnson? A used copy is on sale at the buy/sell forum.