So I re-did a tank recently because the substrate was old, the filter setup was rigged beyond belief, and I had a few new ideas.
So on this 20 gallon long tank, the new filtration setup is:
1 double sponge filter rated for 40 gallons
UGF with 2 inches of seachem matrix on top, topped with amazonia and africana
UGF is hooked to an eheim 2213 full of bio media and some pads for mechanical filtration
then today I finished it off with a fluidized purigen reactor I made with parts from home depot. Anyways, I thought I'd show a picture of the thing and explain how it works:
This is the reactor, it's a drinking water filter casing with fittings to hook to my 2213 return line. Basically I hooked it up backwards, took out the "filter" part of it, and put in a piece of PVC that goes from the middle (input) down to the bottom of the filter. I then cut a piece of poret in the shape of a ring to put at the top of the filter (just to minimize the amount of purigen that may escape). I then put about 200ml of purigen in the bottom, screwed it all together, and then slowly turned the input on (this is key) and slowly but surely increased the water volume until water was shooting full blast out the spray bar. If you turn the water on all at once, the purigen becomes a giant mess inside the reactor, but if you turn it on slowly, it stays suspended without reaching the top of the filter casing.
I did this because those stupid 100ml purigen bags that they sell are a waste of money. Water just does NOT flow through those tight little bags since they're so jam packed with purigen. Now each piece of purigen is maximizing its potential, utilizing 100% of the surface area of each little piece of purigen.
This should work dandy for keeping down DOC's in the shrimp tank, much better than a baggie of purigen anyways.