Originally Posted by geeks_15
Mangroves could work. I have emersed philodendrons (probably the fastest growing and easiest of these 3) and lucky bamboo in an open top tank that also grow with relatively low light. All 3 of these grow fairly slowly, but also don't need much light to grow. You could put a bunch of them in a sump to increase the nutrient removal.
Another plant that would work in a sump, probably better than anything, is duckweed. It grows fast and is great at removing nutrients. I know it is scary to introduce duckweed to a tank, but with surface movement in the main tank it should keep the duckweed from spreading in the main tank. I net out duckweed from my aquariums and compost it. If it ever gets out of hand you could add the goldfish from the pond sump to eat it.
That is what I am looking for. I know of a few plants that this would work well with. And you just gave me a few more. The sump would not be high light at all. But I think it would be really beneficial to have something like this. Especially if you keep cichlids, or have a high bioload in the main tank. As far as the duckweed goes, I think that may be a problem as I am looking at something with baffles in it that would allow the water to flow over them to the next part of the sump. However, if you designed it a bit differently, I am sure that would be an excellent plant to use. And like you said, if it gets too bad, you can throw a goldfish in there for a while to help get it under control again.
As far as the pond acting as a sump, right now that is just a dream for me, lol, but someday, maybe, it will be a reality.