I'm having this problem too. Could it be cold? I'm not leaving my plants to freeze, but its around 55-75 depending on time of day. Heating is expensive.
I do the same thing for the bottom feeders (Snails) in mine, only i have a seperate, hidden small tank that i have several rocks on that I allow algae to grow on that I switch out as the snails devour it.
I will have to try this with seeds! I just got my first batch of homegrown seeds from a...
Those are a type of fern (I read it spreads by spores) that you will find outside all over. It has black/purple leaves that spread along the ground that turn bright red in the fall. It is really a weed