Reef Octopus Essence S-130 Most popular internal skimmer for 2019 All of the modern features of an internal AC skimmer such as a slim profile, air silencer and drain fitting but also a few surprises that simply make your life easy. The most notable
Everyone has an opinion when it comes to skimmers. I am a big fan of #reefoctopus and am currently running three of their skimmers. I have been using their skimmers for the last ten years and found them to be very reliable. Good luck with whatever you chose!
The best advice I can give is to google something like "reef2reef + *skimmer you're thinking about* + issue". That way you can be mindful of each skimmers quirks- when you do that you'll see some people have the same issue that's unresolved and might bug you, while other posts might include replies such as "that's weird, every *skimmer you're thinking about* I've owned has worked flawlessly. I found searching for a skimmer's faults to be more productive than looking up a skimmer's praise.
That being said, my personal suggestions for skimmers for a 125 are either reef octopus, the curve series, or any skimmer by deltec
Reef Octopus has several levels (classic, regal, and elite) and several sizes depending on the size of your tank as well as options where the pump is in the body of the skimmer (space saving models usually marked with an "s" or "sss") or the pump is outside of the body of the skimmer. Depending on the specifics of what you are looking for there is a good chance that Reef Octopus has a skimmer that will meet your application - good luck!