So I currently am using a HOB marine land bio wheel along with a left over top fin HOB for my 20 long planted tank. I am starting to realize again that having to buy the store bought filter cartridges as rather expensive. I actually have some left over ceramic rings that I previously bought. I was wondering what everyone's experience is with either adding ceramic rings to their HOB and also the use of a carbon less filter pad. This tank has been established since December and all the levels look good so I also do not want to mess with something that isn't broken! Any information would be helpful. Thanks!