waterdrop
Enthusiastic "Re-Beginner"
If you haven't already got any liquid ferts for your live plants you could look for the smallest bottle of the cheapest stuff next time you are in the shop, one that includes iron. Putting in a tiny bit of iron in the tank is something that Hovenec has reported to be helpful for the autotrophic bacteria (can't hurt the plants either probably, though I'd probably put less than recommended.)
~~waterdrop~~
~~waterdrop~~