Hello, I just started a 46 gallon freshwater tank 2 weeks ago after being out of the hobby for a good 20+ years. This will house an oscar and pleco until I move out of this apartment and get a bigger tank.

Question #1

I have an API Filstar XP-M and love the quietness and flow. I do not have an airstone but I have the outlet nozzle about an inch below the water surface, this moves the top of the water but it's not really breaking it, at least it is hard to tell. I know you need good gas exchange and did not want to get an air pump with air stone, but if I need it I will, should I?

Question #2

Fish have been in tank for 7 days now (i bought 2 rainbow tetra for cycling) and noticed the water is not really a nasty smell but it's not pleasant either, I just changed almost 50% of the water and it's mostly gone away, for now. I checked the water and I have no ammonia or nitrates but I have had a little high nitrites since I put water in the tank, could this be the smell?

Or is it from a lack of aeration?

Sorry for the wall of text.