Its really just a very expensive powered sponge filter with a second compartment. High density sponges are just about the single most efficient biological and rough filtration media you can get. About the fine filtering pad... you can wrap some felt around the center frame of a sponge filter and get the same results using a mere fraction of the cost of the aquaball.
The smallest sponge filters are good for about 5g each and cost around $6.00 before shipping, you can get ones that are two of those tall for about $10.00. It all depends on your tank size. Sponge filters provide superior aeration, good smooth tank-wide flow and are capable of fairly fine filtration of debris. I commonly get enough out of a 5g sponge I use in a 2g petco hex to make a pot of coffee look crystal clear.
You can use most standard power heads on the 1" lift pipes on the sponge filters instead of using air to circulate if you're wishing to maintain elevated CO2 levels in the water.
Last edited by Thunderloon; 07-07-2011 at 01:36 AM.
Reason: Lost my car keys, nope... not in this post either. Hmm.
There's another way to make a sponge filter that is also just as effective but much easier to maintain.
I can't find my sketch pad right now:
Get one inch pvc pipe, a slip fit (glue) T, a 90° elbow, and and end cap and a sponge. You can use manufactured sponges or custom sponges made with that freeze and drill trick.
Long vertical pipe with intake-strainer on bottom end, on top of this stick (and glue on unless its a tight fit) the T so that you can see through the long pipe, the T part aiming off to one side. Cut a section of pipe long enough to reach out and hold the elbow far enough that the sponge will fit on a short pipe aimed down without pressing on the long pipe. Cap the other end of the short pipe with a tight fitting cap but don't glue it (or you can use a cupping sponge and leave it uncapped). Drill fairly large holes through the short pipe that goes through the sponge.
What you end up with is an upside down J looking thing with a sponge on the hook, if you drop this down in the tank with an airstone down the long pipe and the sideways pipe partially submerged the air will make water climb up then flow to the side down out the sponge while the air itself comes out the top (other end) of the T fitting. You can just yoink off the angled piece of pipe and take squish out the nasty and scrub it out in the sink. Debris that are sucked up into this will be inside the pipe and sponge.
Admittedly its not a forced flow system but it works ok, the trick is the vent-pipe sticking up from the water (only need to keep water from flowing over the top, like 3/4 inch at most) forces the lifted water to go through the sponge.
(For extra credit use a really good air-stone and turn the top into a protein skimmer XD.)