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Re: Questions about Salvinia & Duckweed

David Cooke wrote:
> I have a few questions/observations about Salvinia & duckweed that I was 
> hoping someone might be able to help me with.  I have some salvinia in my 
> low-tech, low-light, non-CO2 10 gallon tank at work, and it reproduces 
> and does well, I have some in my high-tech, high-light, CO2-injected 90 
> gallon at home and it also does well, but when I put it in a bucket and 
> put it outside, it turns brown, and starts dying.  Duckweed is the same 
> way.  I was really hoping to be able to grow lots of duckweed/Salvinia for 
> use in my pond (gold fish *love* duckweed - they will clear out about 4 
> square feed of duckweed in a day or two!)  Could it be that direct sunlight 
> is too much for duckweed/salvinia? Maybe there's not enough nutrients 
> (although I use the water from the pond, which should be *full* of 
> nutrients)?  Any other thoughts/ideas/suggestions?

Contrary to what most have stated on this list, I believe that the direct
sunlight is indeed what is causing the plants to die.  It is not necessarily
the sunlight itself, but the shock from going from flurescent lighting into
direct sunlight.

As an example, I grow my own tomatoes and peppers from seed.  Both of these
LOVE direct sunlight and thrive in it.  However, if I ever put these plants
out in direct sunlight after being raised indoors under flurescents, they
can die in a matter of hours (no exaggeration... I've done it before)!

So... I always wait for a cloudy day to first set them outdoors.  I keep them
in a shady spot for a week and let them have progressively more sunlight
each day (0 minutes the first, 10 minutes the second, 30 minutes the third, 
an hour the fourth, two hours the fifth, etc.)  I find that direct sunlight
is more critical than night-time temperatures when it comes to "hardening"
them off.

I'd give it another try, but put the stuff in a bucket and keep them
in "indirect" light for the first few days.  I'm confident that you will
see much better results by hardening them off progressively.  I don't
think that nutrients are a problem.  Duckweed can survive in almost anything!

David Robinson                          The Discus Page
robinson at ichips_intel.com               http://www.ee.pdx.edu/~davidr/