Hi, I have two reactors, the first is a Deltec for bio-pellets and a Reef Octopus for media, I did a lot of looking around for a third one and have settled on the Nextreef MR1 for GFO. What I like bout them is that the top has two small 1/2 outlets, this will allow me to use a short connecting hose with a couple of 1/2 90 degree barbs for upflow and downflow, this is the only reactor that has nice compact fittings on it and easy to clean - read you can get your hand in to wash out. I will probably sell the Reef octopus reactor and buy a second MR1 if that helps. Have also had a huge Avast, well made but was too large for my 120.