From london@calypso Sun Jan 23 17:14:02 1994 Date: Sun, 23 Jan 1994 16:24:05 -0500 From: Larry London To: london@sunsite.unc.edu Subject: Re: [F] duck weed lowered nitrates In article <1994Jan18.182245.9696@bme.ri.ccf.org> you write: >I have gleaned several good bits of help from this group, >so here is my contribution. > >I have a 29 gallon freshwater tank that has been going for about >18 months with 1 large angel, 1 6" pl*co, 1 large gouramie, >2 dwarf gouramies, 2 swordtails and 2 platies. UGF with 2 powerheads, >plastic plants, some algae controlled by pl*co and occasional glass >scraping. 20% water changes twice a month with gravel vacuuming. >Lighting: one plain old PlenPlax fluorescent. (20-40 watts?) > >After loosing 2 dwarf gouramies, I checked the ammonia (0) and >nitrates (> 150 ppm!) Started twice weekly 20% water changes and >reduced feeding. This brought nitrates down to 40-50 ppm, where they >stayed fairly constant after several weeks. Maintenance resumed at >about 3 times a month. > >I wasn't very happy with this level of nitrates, so I decided I needed >something to eat the fertilizer. I bought a couple of scoops of >duckweed, performed daily rinses and complete water changes for a week >in a quarantine bucket with shop light, then dumped it in the aquarium. > >Nitrates are now constant at less than 5 ppm (detection limit of >Aquarium Pharmaceuticals dry tab tester.) I harvest about half >the duckweed during each maintenance. It pretty much covers the >surface by the next time. > >Simple, easy. Happy fish, happy aquarist.