(04/22/2008) - very high build quality and easy to set up. if only all pieces of equipment were this easy to implement and use! would definately recommend to anyone.

(07/01/2008) - I received my GEO612 last week, I did not sleep that night waiting to set up the reactor, the reactor has very nice finished, it has very nice performance,but, I would like to comments two issues that I found, the first one is in the screws to attach the Eheim 1048 pump in the base plate, it had different diameter that the hole´s plate, just I needed to replace the screws for a little bit more smalls, the another issue is the leakage, I needed to disassembly three times to eliminate the leakage, big problem, I would reccomend to modify the design and to add another kind of seal, regards

(09/16/2007) - This is the second reactor I've run on my tank. Bought a used Korallin C 1502 first. It was difficult to dial in and took much longer to get exactly right. I sold it and bought the Geo. Had it running perfectly w/in 15 minutes, never needed to adjust until my Co2 tank emptyied. Construction is excellent and clean with blemishes or rough spots. No issues with the gasket as mentioned by a previous reviewer. Instructions were clear, concise, and easy to understand...unlike the Korallin instructions.

(06/15/2007) - Very very nice product. Easy setup and very well built. Also looks as if it will be very easy to clean when it comes time to change out media.

(06/07/2007) - This is an AWESOME piece of equipment! Works VERY well and is so easy to dial in that its silly! I would HIGHLY recommend this piece of equipment to ANYONE that wants a good reactor for there system!

(09/08/2006) - I've owned Knop, Aquamedic, Coralife, and Korallin reactors before and this unit is up there in terms of quality/reliability with Knop and Korallin. Ruggedly built (3/8-inch acrylic), very easy to set up and get running. BEST bubble counter on any reactor I've seen- very easy to read and set. Use of the Eheim #1048 is a definite plus. Built-in probe holder that fits Pinpoint probes. The only negatives I have run into is that the feed line is 1/4-inch instead of the standard 3/16-inch airline tubing size. Tech support also seems a bit slow in answering emails. I did not experience any gasket problems as posted by another reviewer. Top gasket went on easy and has stayed water tight.

(06/23/2006) - Leaks very easily from O-Ring...bought this and his Nilsen reactor. You have to tighten the nylon nuts almost to the breaking point to seal it. I made a closed-cell neoprene full surface gasket to the dimensions of the flanges, and this fixed the problem. O-Rings suck.

(12/30/2005) - I am very pleased with the results. Dials the Calcium and Alkalinity to consistent levels with very little adjustments on my part. Well constructed

(06/01/2004) - This reactor is easy to set up, very efficient, and well made. I am very happy with it.

(06/01/2004) - I have had my reactor running since April and I have to say it has been the best unit I have ever owned. The previous reactor I had purchased was a dual chamber by a DIY company and it was poorly constructed. The GEO reactor is built like a tank! The seals and joints are solid This reactor is so great I just got one for a friend of mine and installed it on his tank. If you are looking for a reactor this is your best bet.