I had Korallin C1502 and sold it to buy a Geo 612.
The Korallin uses less Co2, but is much more difficult to dial in, and keep dialed in. The Geo is pretty much set and forget. Do yourself the favor of buying a good needlevalve/solenoid the first time. This will save you money later, and will make things much easier for you in the long run.
I'm using the RF solenoid/gauge/needlvale combo I bought from Premium Aquatics. The only complaint I have about it is that when the power goes out or fluctuates briefly,and then comes back on, the solenoid stays closed, which doesnt allow Co2 to flow from the tank to the reactor....which means my reactor isnt doing anything other than circulating water through itself. I think I might have a regulator with a minor issue, as I havent heard anything like this from anyone else who has this regulator.
If you buy the Geo, you will need to buy a Co2 tank, a feed pump of somesort, (I use a maxijet 1200, but I know several people use an Aqualifter pump and connect it to the outflow of the reactor thereby "pulling" water through the reactor as opposed to "pushing" water through it like I do), the media, (I use the Gen X media which is the same style as the Schuran Media, its larger pieces of coral skeletons...look like little finger bones almost), and the regulator/needlevalve/gauge. When you purchase the reactor, you are only getting the reactor itself. Several places, (like phishybusiness for example) will sell you complete reactor packages.
Nick
