I just replaced the carbon in my aquaclear. It currently has 3 inserts biomax pellets, carbon and a sponge that is coarse like. Recently my tank had some more issues and I realized it was right when I was suppose to change the carbon but forgot about it I'm not saying it was a cause of the problems but iv heard leaving carbon in past the change date is bad. If the benefits to my current and future plants, fish, snail are great then I will make sure I remember from now on but was wondering if I should just replace it with a different insert. I think they have a foam or other different ones...or anothe one of the inserts I already have....what do you guys think?