My tank is a 75 gal with a 30 gal Sump/refugium. I use the refugium to house 2 inches of mud and Anubias/Crypts/Java Ferns. For biological filtration I use 2 L of Seachem Matrix. I have a 500 g/h pump in the return.
Current Fish:
1 x Sailfin Pelco
20 x Zebra Danios
15 x Pearl Danios
5 x Cherry Barbs
5 x White Clouds
10 x Black Skirt Tetras
10 x Neon Tetra
1x Algea Eater (in sump)

Parameters: pH 7.8, GH dKH 6, Ammonia 0.0, Nitrite 0.0, Nitrates 20. I perform 20% water change 2 times a month.

I know some fish have more of an impact or higher bioload then most, is it possible to add more Neons to this tank? I really want 20 Neons if possible.