Betta Filtration??

Since a one gallon water change won't take long at all, you could even do it twice a week with minimal disruption to the betta's day.
 
Have you looked on the bottom of the filter. I had those type filters for bettas in the past and mine had a button on the bottom that would slide back and forth to give more or less filtration. I used the lowest setting for my bettas. It was barely a trickle. Good Luck!
 
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