Subject: Control of algae in planted aquaria

From: [email-masked] (Kevin Conlin)
Date: Mon, 18 Mar 1996 21:33:12 GMT

A friend and I have been running experiments on our planted aquaria in
an effort to get good plant growth while minimizing algae.  We've been
fairly successful, and our observations are consistent with the
following hypothesis:

  When light, CO2, N, K, and all micronutrients and trace
  elements are present in slight excess relative to the amount of
  phosphate available for plant growth, certain higher plants in the
  aquaria are able to out-compete algae and cyanobacteria for the
  phosphate in the water column, starving them of this essential
  nutrient.

("Certain higher plants" refer to fast-growing aquarium species such as
Hygrophila polysperma and Lemna minor.)

What we'd like is some theoretical or experimental evidence for the
hypothesis.  If we could get a reference that shows that (for example)
duckweed can utilize phosphate concentrations as low as (say) 10ppb but
most species of green algae require at least 20ppb and blue-green
cyanobacteria need 50ppb we'd have strong support.  Any explanations or
references would be greatly appreciated.  I'll e-mail a draft of a
paper we're writing to anyone who's interested in our results (it's
kitchen science, not the usual rigorous stuff, so it's not too painful
to read).  Thanks
--
Kevin Conlin                          "We're Canadians.  We HAVE to be polite"