A few things to keep in mind with AC
filters. The sponges will last for years, so don't toss them until they start to crumble. You can use 2 sponges to double the area for bacteria. If you are using 2 sponges, you can put some filter floss, between the 2 sponges for finer filtration. The floss will clog fairly quickly, but you may want the extra filtration. How often the filter needs to be cleaned depends on the bioload in the tank. The filter will work better if kept clean, that is removing the solids from the insert. Regular cleaning will help keep nitrate levels low.
Good luck and welcome to the site.