Okay so I have a Penguin Bio Wheel 150 in my 20 gallon tank. It has 2 slots for filter cartiges but I don't need 2 cartridges the 1 catches everything . I'm more interested in adding some more forms of bio filtration. The main cartridge should go in front to filter out the particles and only allowing water through. I was wondering if there was any way I could make my own cartridge and use something like bioballs to add more bio filter? Just wondering thanks everyone !
Also yes I notice the typo in the title using an iPhone.
Also just noticed my filter is overflowing through the spill way and sides
And here over the side next to the bio wheel