when it's time to change the filter pad, try to seed the new pad for a few months first. Do this by squishing the new filter pad in the filter with the old one so it can pick up the bacteria from the old pad. Leave it like this for as long as possible before throwing away the old pad (At least a few months if you can). Then simply throw away the old one, leaving in the new one that is now chock full of the BB you need! Doing this will prevent you from having to cycle again. I've had the same pad for almost a year and my tank is doing great so don't be in a hurry to change it. Besides it saves money not having to replace it right? lol