If I use the bubble floating as witness, it's a little too slow.
Make sure that your "baffle" does not go higher than the apex of the chute of the Aquaclear. Because, Using a sponge to restrict flow has a risk of clogging and make a massive spill.
A good way to restrict an Aquaclear is to use an intake cover sponge, It will slow down the flow and prevent your betta from getting stuck on the intake. You can also put the flow control to minimum for the time being. Your setup seem to be quite "young", with time the filter will slow down. Your on the overkill side for a betta, and that's good, but it will take some time to break-in, but you are going to love it. Too stagnant water has a tendency to promote fungus's and you don't want your Betta's fins dragging in that.
Also try to put a black background to see how your beauty comes out, with a darker environment.