plants as filters?

Aquarius Keeper

This is a topic I'm curious about -

Plants consume ammonia and nitrate, and plant photosynthesis creates oxygen - so theoretically, plant life is 100% capable of maintaining water quality, right? And that's how small standing ponds without a current support life - the plants keep the water clean for the animals, the animal waste feeds the plants.

So how possible is that on the micro-level? I mean, how planted would a 20 gallon have to be before it could support 1 Guppy with no electric filter whatsoever? How planted would it have to be to support 2 guppies? How many fish could ultimately be supported by this method before the fish were producing so much waste, the plants would be overwhelmed and ammonia would start to build up?

Has anyone had any experience or done any research in this areas It's something I'm interested in experimenting with (humanely, of course)...

Jonathan

iamntbatman

The science is all sound, and I know people have done this before. I think you could support one Guppy in a 20 gallon tank if the tank was *very* heavily planted. You'd also want to make sure you had fast growing plants because they'll consume nitrate at a higher rate than slower growing plants. Watersprite, Hornwort, Duckweed and water lettuce all grow at a pretty fantastic rate. I think it would be best to provide some sort of water movement just to be safe, even if it was just an airstone. Also, even if you could have enough plants to completely control nitrate levels, you'd still want to do water changes on a fairly regular basis. As fish (and plants) grow, they use up trace elements in the water that are only replaced via water changes.

Aquarius Keeper

mmm... I bet I could support a dozen guppies if I really worked at it. Of course then the tank would be overrun with fry...

Seriously, though, thanks for the info - yeah, airstone is a good idea, definitely - and I'd do water changes even if my nitrates are 0 ppm, or at least top it off for evaporation (I'm in Southern California).

Anyway, I need to stop dreaming up future aquariums and see if I can make the one work. (although I think I will start cycling that shrimp tank...I'll get an air pump for that one too...)

Kim

The water may get kind of grimey with all the plants and no mechanical filtration. Leaves do die sometimes. Just a thought.

Aquarius Keeper

oh yeah, totally, in addition to the planed stuff, the tank would probably have to be an algea garden for it to work, and I'd have to trim away dead bits etc ... not easy, definitely (a dozen comfortable guppies would be super hard) - I think I got the idea from a quirky aquarium store in Korea-town, old guy has been keeping some of those aquariums for decades and in a lot of them it almost looks like he's cultivating algae...