Introduction.  The email below inspired this particular page.  Sure, it took a couple weeks, but I was busy.  LA  May 18, 2006

Manuel deLossantos, April 29, 2006
I`m one of your members. I watch your web page everyday and wanted to know what do I need for a sponge filter. Or if you can send me a picture of it set up, I would really thank you.

A:  Here's a picture of a sponge filter with some cherry red shrimp "harvesting" whatever's growing on this sponge.  This is half of a 20-year old Tetra Brilliant.  TetraWerks stopped making them a few years ago.  Hagen makes a close copy of it.  Jungle, Lee, Penn Plax, and Ginger all make good sponge filters of an entirely different design.  They all work well.  You just hook 'em to an air pump and they start working.  They need about six weeks to grow a good bacterial base.  They filter biologically and mechanically but not chemically.  LA

Let the info flow ...

How Sponges Filter Your Water.  Water flows thru the sponge causing  beneficial bacteria to colonize its surfaces.  The bacteria eat harmful fish wastes and change them to fairly harmless substances.  The sponge also collects small chunks (but not big chunks) that otherwise tend to drift in the water.  Sponges will not remove colors or smells.  You need carbon for that -- and regular water changes.  Your sponge filter also aerates the water by turning it over 24/7.

Economical.  Here’s a typical sponge filter often seen in larger tanks with large populations of fish.  Lees, Jungle, Penn Plax, and Ginger all offer about the same product.  These are not decorative.  However, they are very functional.

Air-Powered (usually).  Small air pumps “power” sponge filters.  You can put a powerhead on some home-made sponge filters.  Before you do, realize that its capacity to capture “chunks” greatly increases.  These high powered sponge filters work too well.  They clog very fast and stop filtering unless you clean them often.  The air-powered filters need much less maintenance.

Bacteria-Powered.  Biological filtration takes about six weeks to come on line without a jump start.  Take your virgin sponge filter to a well populated African cichlid tank.  Squish it into the gravel and squeeze it several times in whatever’s on the bottom.  This will inoculate it with the bacteria you need.  You are now ready to toss it in your tank.

Great for Baby Fish.  Power filters suck up fry and weaker fish.  Under gravel filters will also suck in newborn fry.  Sponge filters grow tasty critters such as rotifers on their surface.  Fry consider them quite edible.  Beside saving the lives of your fry, your sponge filters also feed them.

Economical (even cheap).  You can find really cheap sponge filters -- and they do the job.  They're not fancy, just reliable.  The less costly ones require the least effort.  Hook the airline to your air pump. Attach it to your sponge filter.  And toss it it the tank (the filter).  We have had some customers that toss the air pump in the water also.  We do not recommend this practice, but it does make a fun topic for discussion.  Anyway, because they’re cheap, you often see sponge filters used in fish rooms with rows of tanks.

Emergency Water Clarifier.  Been overly generous with the food lately?  Water a bit hazy?  Drop in a working sponge filter.  It will clear your water overnight unless you poured milk in your tank -- another practice we do not recommend unless you’re growing infusoria.

Different Sizes.  All the sponge filters work.  You need larger ones for larger tanks.  Because they bend, the little ones work in those strange containers with small openings in the top.

Easy to Hide.  Not everyone wants an ugly sponge in their tank.  They work almost as well when you hide them under your gravel.  The triangle-shaped ones work best for disguising, because the filter stem comes up in the corner.

Replacement Sponges.  As time and a half goes by, all the sponges wear out or get eaten.  The biggest threats are apple snails.  They’re voracious little beasts.  Live-bearing snails also eat sponges as do crayfish.  Large fish like to tear off chunks for entertainment.  But then, they usually have little else to do all day long.  You can usually find replacement sponges if you look around.

Surface Area.  The larger your sponge’s surface area, the greater your filter’s capacity.  Some companies cut strange shapes in their sponges.  Others cut grooves.  Anything that increases the surface area works.

Home-Made Sponge Filters.  Captain Jack made 50 of these for his breeder angels.  When his wife made him go on vacation, we bought these and sold them as part of a quarantine set up.  These filters will accept a powerhead.

Hydro-Sponge Filters.  If you attended the Midwest Cichlid Association’s EXPO 2006, you saw a lot of these sponge filters at work.  Note the grooves.  Discus keepers in particular love these filters.  Their construction allows bacteria to also colonize the bottom surface.

Tetra Brilliant Sponge Filters.  Tetra stopped making these a while ago, as well as a cheaper uni-sponge un-grooved model called the Billi (billig = cheap or chintzy in German).  They modified the Brilliant before they discontinued it, but did not make it easier to use -- just the opposite.  The suction cups wore out fast, but they did send us a couple hundred free ones (which also wore out).  The suction cups hold the filter upright which increases its effectiveness.

Hagen Sponge Filter.  Identical to the discontinued Brilliant in white instead of green.  Their sponges clog up faster and are harder to clean.

Floaters Barely Filter.  Without the suction cups, these filters want to float.  Water changes cause bubbles to adhere to the sponges and make them float.  Floating on the surface, they filter poorly.  .

Anchors.  You will need lead strips or some type of weight to keep these guys vertical and to keep them from floating.  You will also need to squeeze the sponges to get rid of the bubbles.

Good Flow-Thru.  These holes enable water to flow thru the sponges and up the exit tube.  Unfortunately, the holes also increase the fragility of these tubes. 

Algae Substrate.  Sponge filters make an excellent site upon which to grow an algae ranch.  Algae eaters do not like this particular species.  You remove it by pulling it off by hand.

Java Lance Fern Substrate.  Java lance fern also latches onto these sponge filters.

Age Happens.  No matter what, these sponge filters break down over time.  However,  You should easily get ten years out of a sponge filter unless you put it in with something that eats them.

Sponge Cleaners.  You need to squeeze your sponges on a regular basis.  Little guys like these algae-eating shrimps also help clean your sponges.  LA