For A Diy Sponge Filter

[woodstock]

If I made my own DIY sponge filter, how would I know what capacity it would be able to handle? And would putting two in a 10 gallon be too much?

 

[woodstock]

Also - If I were to choose my own sponge, how would I know it's aquarium-okay? As in, if I just went to walmart and got a sponge. How would I know it's okay?

 

[OldMan47]

If you go to a local store and just buy a random sponge, it will likely be a closed cell sponge. That kind is much better at holding water than an open cell sponge so it is the commonly available kind. For a filter element, you want an open cell sponge. It is a poor sponge for soaking up water but allows water to flow through it fairly easily. A sponge filter is always made with open cell construction because a closed cell just doesn't get any flow through it to do the filtering.

 

[Tolak]

An Aqua Clear 70, fairly common HOB filter, uses a sponge that is roughly 5"x3"x3". While they do sell these filters with bio media now, originally they came with a sponge & carbon. That size sponge was designed to do the mechanical as well as biological filtration for a tank up to 70 gallons. Just guessing from having used them for years it would be a fairly lightly to close to average stocked 70 gallon community tank. That size filter & sponge would do really well on a heavily stocked 30 gallon tank. This should give you a ballpark idea of the stocking a particular size sponge will handle.

Look for cushion foam, used for upholstery or other projects, this is most often open cell. You want to find the really cheap stuff, this does not contain fire retardants. Another source is pond filter media; these often use oversize open cell sponges.