I have a Vertex 180i on my system, probably 160g total capacity. Quality of construction and materials would be hard to beat. Seriously heavy duty.
I did have some problems... I bought this from a friend that had bought it new, couldn't get it to work, and threw it on the shelf. I brought it home, disassembled it, and found that the impeller shaft was broken. Since I was not the original owner, and it was a year old, I had to pay for a new impeller assembly. $50. Used it for 5 months, with very good results, and it quit working on me. Pump bearings are obviously chewed up. Contacted Vertex support. It took some talking, but I got them to break down a new unit and send me the entire pump assembly. $200. Since then, it's been running flawlessly. Honestly, I figure we got a unit with a bad pump from the factory. Broke the 1st impeller, and eventually burned up the bearings... I would say it was never quite right. The new motor is way quieter than the old one ever was. Since my friend chose to ignore the problem and put the unit on the shelf, well, we didn't get it serviced under warranty. More my fault, and my friend's fault, than Vertex's fault. They did go to some length to assist me, even though it was not warranty work.
IMHO, my 180i is properly sized for my 160g system. I don't know that I'd put this on a 75g tank. Probably recommend a slightly smaller version.
I've had Reef Octopus skimmers. They work, but take much more 'playing around' with than my Vertex. Once broken in, it's truly been a set it and forget it skimmer. Clean the cup every week, and let it run. My old SRO1000SSS worked, but I had to mess with the water adjustment every week or so. Not so on the Vertex. Ran for a year without touching any adjustment. I raised water level in the sump by a couple inches a month or so back... had to adjust it then, but you'd expect that.
The friend I bought my Vertex from is now running Skimz skimmers on 2 tanks. Quality is good, though I'd still give the higher quality win to Vertex. He's had 1 broken water gate adjustment rod... no other quality problems in, what, 18 months? Similar to my old Reef Octopus, he has to 'play' with the adjustment on his Skimz every once in a while to keep it skimming.
