If your going to paint , I recommend using oil based paint . I found when using a water base paint , the coverage on glass comes out with streaks and may need several coats .
I use black paint for freshwater background , true blue color for saltwater .
Odor from paint never was an issue , you could use a small portable fan to speed up the drying time .
If you need to apply a second coat , make sure first coat is dry. Use the foam type brush / roller , that also works best . Regards