I used a Remora for 2 weeks, CSS for 5+ months. Here's what i observed:
1. Remora skimmed 4 days = CSS skimmed 20 mins (Yep, my CSS went nuts the minute i took down the Remora and turned on the CSS)
2. Remora skimmate: wet yellow/brown Vs. CSS skimmate - wet dark brown (sometimes even black)
Remora - Loud hissing noise
CSS - Silent humming noise
Remora - Hard to clean the bottom of the skimmer. There are tons of scums in the skimmer which i can't clean.
CSS - Easy to take apart
CSS - Big pump
Remora - The bigger the pump, the bigger the skimmer's performance. So if you want it to skim really well, you'll have to get a big pump.
That's just my opinion on the skimmers. Correct me if im wrong
I'm one of those fishnutz, who are actually nutz.