I've always left mine on? There is no cartridge in the filter, just a biowheel (which I've never had before). Right now there is only Fang in there, so minimal bioload.
Speaking of bioload and only having Fang, how soon should I add tankmates for the tank to run well? I'm assuming he alone isn't enough to create enough byproducts for the tank to settle and the plants to eat. Should I be feeding the plants too? Suggestions for food? (I'm in Canada, so I may not be able to get some things)