I don't currently have a GFO or Carbon Reactor though I do run carbon in a small mesh bag inside my filter sock. I am looking at the BRS reactors and was hoping for some opinions. My tank is 75 gallon and I am quickly running out of space beneath it with my sump, ATO, dosers, supplies, and a cerebra controller that I still need to mount. While I am sure I could rearrange everything to fit a couple of reactors in, I started looking at the combined Carbon/GFO reactors, specifically the BRS GFO & Carbon Reactor Deluxe. It sounds like going this route is a bit more wasteful since the carbon needs replaced more often than GFO, but are there any other disadvantages? My other thought is going with the BRS Dual reactors, but I know this will force me to get creative to fit them in. Appreciate the help.