I read that more O2 would be good for my fishless cycle. My father had a 40g filter he offered me and it could put more O2 into the system. Are there any problems with too much filtration? I haven't read anything to said so. I really just wanted an air pump with some air stones. Would that be better?
There's never a problem with too much filtration. Your dad's filter only creates more surface movement, so you'll get more O2. Air pump does the same thing, but it doesn't filter water or create current.