[QUOTE=Jay_Bunny;881056]I would say 1.5 is too much for a 20L tank. I only keep up to 4 rats at a time in a 20L and its never for very long. That's just too much ammonia building up.

I have to change the bedding twice a week.
I'll agree, 1.3 might be better in a 20 long.
When I build my rat rack they will have more space, but I will still keep them in groups of 1.5. I just wont have to change the bedding as often.