filter and maintenance help

hi i have a 110 gallon tank with a canister filter. I was wondering how often do you need to clean the canister filter. ive heard anywhere from every 2 months to every 6 months to once every year... it confuses me. Also, how often do i need to change out the sponge filters and the activated carbon and ammonia crystals? i am afraid that if i change them out too early they will take all the beneficial bacteria out of my filter, and that could have bad effects on my tank and fish.