Java moss has a tendency to colonize filters, so does duckweed, but non-floating plants have a tendancy to clog filters. I have java ferns that go into mine, but i have to clean them out otherwise they can stick the impellers. If you're looking to filter the water with plants I would suggest getting some pumps and a relay-plunger shutoff and make a vegetative filter in a refugium-type thing or a sump