Hi, I used AqAdvisor when setting up my tank. It gives you a decent idea. My tank is half the size of yours with similar sized fish and I have 30 in there with no problems.
As for brown algae, I hear a lot of times that it appears in new tanks because of the silicates, however in my own experience I still have a small amount after a year in my main tank, but non at all in my new tank. The difference is the lighting. I was talking to someone else about this and they said that after they moved their tank to a different place in the room (lighter) the algae disappeared.
As for brown algae, I hear a lot of times that it appears in new tanks because of the silicates, however in my own experience I still have a small amount after a year in my main tank, but non at all in my new tank. The difference is the lighting. I was talking to someone else about this and they said that after they moved their tank to a different place in the room (lighter) the algae disappeared.