Oh hey, what kind of filter are you using for your tank? I had the same issue with my betta's 5G heated tank. But I solved it by using a piece of plastic water bottle over the output of the filter. This website saved my dragon scale betta, it's where I got the idea from :) http://www.bettaboxx.com/betta-care.....filter-baffle/

So this may help you until you can get a sponge filter ^^

i tried the water bottle thing and the only reason i dont like it is because it makes the lid of my tank sit slightly wonky and puts my light too close to the water
for now i have everything baffled with his silk plants, he gets around pretty ok (hes a plakat so thank god he doesnt have long find weighing him down) but sometimes he gets stuck in the current so he tends to avoid the one area of the tank. i just upgraded him from a 3 to a 5 so i want him to be able to use it ;;
the filter i believe is a tetra 10i? the whole set up with the filter and tank was a gift so i'm not 100% sure.
i might try stuffing a loofa in the filter output as suggested by the beta group i'm in haha

Oh yikes. I got a different light setup with my tank. But my tank is one of those $30 Walmart kits heh. The filter I got was the Whisper Quiet Filter, had adjustable flow settings, however on Low, the outflow was still a problem for my betta. I got an old nylon sock covering the intake (have a sand substrate so needed to not kill the filter), then the water bottle, but I did have to trim it until my cover would sit flush. And it's worked so far for me, but yeah it would totally depend on the type of cover you got. Haha, actually now that I think of it my filter is closely like how yours is.

A loofa would work! I've heard of a plastic diverter being used with good results as well that sits in the outtake