I will start with a picture of my pump...
I learned from another location, from someone who supposedly helped design the Evolve series, that the pumps for the Evolve 4 and 8 are rated at 100 GPH. WAY too much for most fish IMO in a 4 gallon tank, let alone a Betta. From another user, on here I believe, I learned that at it's lowest setting, it is still putting out 55 GPH.
I researched some methods that others used to reduce the flow. I liked them, but I wanted something a little different. Also, I wanted to be able to fine tune the flow and easily.
So I went to Home Depot and put this together. The original tube was I believe 1" ID. Or something close. Either way, what I purchased was 3/8" OD x 1/4" ID Tubing, which fit right inside and snugly to the tubing that came with the pump. I also purchased a Quick-Connect Lead Free 3/8" OD Straight Valve.
I measured the length of the original setup, and matched the best I could with the new setup, which really wasn't that hard. I used the old tubing as a kind of flange or connector for the smaller tubing that is connected to the valve.
Right now, I have the valve turned a quarter closed. I feel that between this and the slightly smaller size of the tubing, I should have reduced the flow appropriately.
However, it does still seem a little fast for my Betta. He does ok in the current, where there is current. But I still find him resting near the filter intake.
So I also added a Fluval Sponge at the filter intake, hoping that would reduce the flow a little as well, and it really did nothing.
I am also open to better filtration ideas as well. I just have not had a chance to look into these.
I will reduce the flow even more once the tank has fully cycled. I do not want to reduce the flow anymore right now while the tank truly cycles.