This is a difficult question and one that I get asked quite frequently. When asking which is a better skimmer I think it is what matters most to the user. I will always use Tunze, I have used other brands and perhaps it is just stubborness and simply what I am used to but I like alot of the features the Tunze skimmers offer. I have a 120 gallon reef, the main animals are a 16" Gigas clam and a 2' Diameter Yellow ritteri, their are a few leathers and some acros and lots of mushrooms. For fish their is a Desjardini, three chromis, a pair of rose skunks, a lightning wrasse and a sailfin blenny. I use a cabinet kit 19gca. The heart of this system is a 235/3 skimmer, the 230/3 is the stand alone equivalent. I like the Tunze skimmer because it cannot overfill and pour over, when the cup fills skimming stops. It is very small. The motor produces almost no heat as it draws only 22W. The unit is easy to use and clean, the cup simply lifts off. The adjustment is very stable and so is the foam production. A EuroReef is definitely more powerful. It uses a big motor that produces a fair amount of heat. It is unstable in my experience and frequently foams over if it doesn't agree with a supplement you have added. These are things I don't particularly like about it. It is still a very good skimmer though and I really can't knock it, many people seem pleased with them and of whats on the market I consider it a quality product. I would definitely get a top off system either way, the Tunze can handle at max a 1" fluctuation and really works best if the water level is constant. The Euroreef recommends a constant water level as well. I believe they recommend 6". For our units you just build a shelf or hang it to the appropriate depth which is about 3" submerged. The other factor is flow through, if you are using your sump pump to generate flow it is likely that it will be a poor choice, I find anything above a 5 times turnover is too much turbulence for skimmer function. I think I would recommend a bigger sump, if possible. The Oceanic Model 1 would be a good candidate, model 2 even better, your sump sounds a bit small at barely over 10% of tank volume. I hope this is some help.
