So.. I've had my tank for a few months now. The filter media is getting extremely gross and gunked up. I have a Penguin 100 HOB filter, with biowheel. Is it okay for me to change the filter? When I first started my tank, I was told I never needed/should change my filter. What's the next step for me here? Do I buy a penguin refill designed for my filter, or just any random media, and cut it to fit? Thanks! 8)