I am new to the whole plant thing myself. I do know that a lot of people here and on other forums suggest not using Carbon with planted tanks. Others even say its a waste of money even without the plants. I have wondered this myself. I use a Bio-Wheel filter and I haven't seen cartridges without the Carbon. Maybe while someone answers your question better they could tell me if there are any other options besides the pre-loaded carbon filter cartridges for the Penguin Bio-Wheel Filters.