I have found hornwort to be useful in algae control. This plant grows
extreamly fast under bright light (metal halide). Often growing 4-5X it's
length in a week. I would simply pinch off the growing tip and throw out
the bulk of the plant. Thus removing any traped nitrogen and phosphorus.
The plant soon grows to cover the surface of the aquarium. When this plant
is growing well, small bubbles will be seen coming from the tips of the
leaves at least one every 10 seconds.