In a fish only (w/macro algae) system just how much gets "used"?

ArcKatana · Jun 30, 2015

Something I've been wanting to ask, but have never gotten around to it:

What exactly is being taken from the water in a fish only (with macro algae filtration) system?

I've got fish breeding in water that is nearly six months old, with the occasional top off of tap water, and the very random five gallon water change (30G system).

I'm sure carbon / chemipure is pulling something out, the MacroAlgae is pulling iron/nitrates out, but what exactly are the fish pulling from the water?

I ask as you're the only one I know who could give me an answer I'd understand

Thanks!

Randy Holmes-Farley · Jun 30, 2015

The fish pull out nothing significant except oxygen. They get essentially everything else from foods, and in that sense (digested foods) are a source of all sorts of chemicals that they release to the system, including trace elements, ammonia, and phosphate.

The macroalgae also pull out more than you list, including phosphate and trace elements.