I appreciate the reply, thank you. I was referring to replacing the filter cartridge, not cleaning it. I read that it's not a good idea to change those very often since they hold the BB. Since it's only been a couple of months, I was thinking it was too soon for a full replacement.
I just did another cleaning and water change and rinsed my filters as well as the sponges as you had recommended. That had not been done yet because I was afraid of disrupting the BB, but it sounds like it was long overdue. I will add that task to my routine cleaning.
How long do you suggest keeping my old (10 gal
) filter running along with my new 20 gallon filter in the tank? I was thinking a month should suffice, but I don't want to pull it too early.