Hello Mario,
I'm not sure that there is an optimal density of cats. I think that some species even need to be gregarious
. But you are right, the more you have the more often you must clean!
About bleach, I use it also but I know that it doesn't kill everything.
There is another product, I don't remenber the name right know but I will tell you later, used in hopitals, which is more efficient.
Direct exposition to light containing UV (sun
, artificial bulb) is very usefull too.
_________________
@+ Patrick
________________