question regarding HOB skimmers

I am in the process of starting my 125g saltwater tank and alot of people have said that HOB skimmers are not as good as in sump models. I'm just curious as to why? Don't then do the same thing?

 

Not as good meaning, not as effective. The sheer size of the in sump models vs the HOB "generally" makes them more effective. On a large tank, like a 125, folks usually will run a sump. Why have a HOB skimmer that's visible, sometimes in the way, and less as effective as a model that's hidden in the sump and superior?

I'm not saying that there isn't many great HOB skimmers that can get the job done. I've got a hang on skimmer and hang on fuge going on my 29 gal build, because I specifically did not want a sump for this build.

 

Thanks for the reply. I was wondering because I was looking at a used HOB skimmer and unsure if I will run a sump or not. Got a great deal on it..so I guess I'll have a chance to see if I like it or not