I'm not sure if anyone has seen this or mentioned this here, but I thought I'd mention it since it's a REALLY effective way to reduce the current in your tank created by a filter, and I highly recommend it for anyone who has a betta who hates the currents created by their filter.
I just tried it today and not even two hours after I put it in, xD Shota made a ginormous bubble nest o.o (which is odd since he usually never makes bubble nests unless he's able to see a female.) He's swimming around so happily x3 I'm really glad I stumbled upon it.
Anyway, here's the article
! :) I hope it helps people like it helped me!