This is why I like pre-filtering at the overflow. It’s easy. Put the filter in the easiest place to do the maintenance. This took me lass than 5 minutes to change out both sides. I pre cut the filter so I remove the dirty one into a 5 gallon bucket and place the new filter in. Move the step stool to the next over flow and repeat. 5 to 10 minutes all the overflows in my fish room are changed.