in-tank fuge for severums?

[fish23]

I want to put a hang in take diy fuge (plastic container with holes) in my 55g tank in order to help with nitrate reduction. Planting the tank not an option because severums make tasty treats of plants. What would be a good low light requirement plant that grows rapidly and severums would enjoy eating extras that grow out of fuge? I was thinking of java moss but if the severums don't eat it I don't want it to take over the display. Any adivice would be greatly appreciated.

[twig]

could you grow hornwort in there?

[fish23]

only have 40w light on tank so less than 1 watt per gallon and tank is brown water from driftwood used to buffer ph, the severums seem to love the muted environment but not great for plant growth. What is the light requirments for hornwart I could add a small 9 to 13w cpf lamp over fuge if needed.