In article ,
"john east" writes:

I'm always careful to maintain the green bacteria in the sponge filter of my
underwater aquarium pump (fresh water), but i still get a dark green algea
growing on everything including any live plants i put in.

The plants never seem to last long. The tank is not near a window, but at
the back of the south facing room. I change ten percent of the water every
week. Reentrant any suggestions please, to get plants to live long and
without the algae?

The light you have is useless for plants. You want a growlux type light,
or a warm white (2700K) is also a reasonably good match (need plenty of
red component). However, you would need higher power too, or just a
little sunlight will swamp whatever you provide artificially. I rather
imagine the algae will benefit equally though. Algae grow on the
nitrogen from fish (or other) droppings, or rotting vegetation.
I used to keep fish, and algae was generally a sign that you weren't
cleaning the nitrogen (droppings) out of the tank often or well enough,
which will ultimately turn into ammonia. Don't know what your green
bacteria in the sponge filter are, but I used to disinfect and clean
the filter more often than anything, but make sure that in removing the
filter, you don't let any water drain out of it back into the tank,
which would be highly contaminated with nitrogen products. I didn't
change any of the water weekly, but did change it all when cleaning
out the whole tank, perhaps every 10 weeks (don't recall precisely
now). With those measures, I didn't get any algae, and plants grew if
you had enough that the fish didn't eat them faster than they could
grow.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]