I also have a 2 tap manifold in my air line. This means that I have a spare tap and if I feel the flow rate is too strong I just open that tap a bit to bleed air into the room so there's less going to the filter.
The one way valve is to stop water getting sucked back along the tube and into the pump.
This is the only filter in my betta's tank and it works fine for me. I have the Aqua One sponge filter in my link and an Eheim air pump. it is pretty quiet, it is sitting on an old filter sponge to dampen any noise. Some pumps and some sponge filters come with air line tubing, some don't; some come with one way valves, some don't. Read the packaging or item description on-line so you know what you need to buy and what comes included.
The one way valve is to stop water getting sucked back along the tube and into the pump.
This is the only filter in my betta's tank and it works fine for me. I have the Aqua One sponge filter in my link and an Eheim air pump. it is pretty quiet, it is sitting on an old filter sponge to dampen any noise. Some pumps and some sponge filters come with air line tubing, some don't; some come with one way valves, some don't. Read the packaging or item description on-line so you know what you need to buy and what comes included.