Betta Filter 5 gallon

I have Penn Plax Cascade filter with spray bar in my Betta tank. It has sponge so I took out the cheap carbon to use two sponges so I could rinse one out in tank water once in awhile and still have the other working and not create a cycle.

Now I have purchased some good carbon and I am thinking I should have some in a hose bag small amount I could squeeze in.

I am currently doing to 50% water changes a week.

Thanks,
Tamara

Thanks for the help. Great advice.