The Puffer Forum

Sounds like a heck of a lot of work & expense, when fishless cycling is not only free (well--the cost of a cheap bottle of generic ammonia), easy & takes 7-10 days...

PP, it's more than that though, we're talking about protein eaters, excess nutrient consumption, nitrification, solid waste metabolizing...
Only thing I think that sucks, is you need the output of the water above the surface, parallel to the water, if you don't have plants...
The bacteria collectively makes a ton of CO2 since it's all aerobic operations, and if you're output is below water, it's like a CO2 reactor.
So no skimmer, no long term detritus, probiotics coming from the bacteria as well for the fishies... I've been recharging my purigen though for about 2 weeks now, and water quality/clarity has not dropped...
/shrug

My FX5 Fluval though holds 5.9 liters and it's prolly pretty close to 1 liter per pound volume wise, might be little less, I don't have mine spread through the FX5 trays very well.. left a little extra room for movement above the surface of the media.

Oh, I forgot to mention though, supposedly you can run the system with JUST the bacteria and no TBPC.
But, you don't get the nitrate reduction.

I'm going to be testing this next week when I set up another tank....