20 or 25?
how many topics can we actually choose?
It should be 20.
You can change it in Topics Settings:
John Waters so i can have 40 topics?
Andre Gois you can probably have more. I dont know if there is a performance hit, or a max. The only thing is the topic selection at the top of spaces with more than say 8 topics is going to look a little messy an perhaps counter productive, just my thoughts.
I have 40 topics, because of the number of spaces I have created (15 or more I think), but I have only allocated 6 max to a space for the above reason (appearances)
They wouldnt have put a "max topic" option, unless there was a reason, I suspect perfomance, but that is a guess.