funny, most would say an aquarium is easier than a pond. I know I never had issues re aquariums and had to learn re a pond but that's because nature didn't have much say with my aquarium! They're basically the same, after Mother Nature is left from the equation. And I thought saltwater was much more maintenance than my freshwater aquariums. Then I sort of applied what I'd learned from ponding to saltwater and now, it isn't much different there, either. Most people would be surprised to learn I've kept saltwater for over a decade now WITHOUT any filter other than live rock.
When I did my first saltwater setup, I cheaped out, and am using a 10 gallon rated hob filter, not sure it is doing much other than water movement, which the powerhead is doing better.
I am having zero problems, no protein skimmer, no sump, and literally all the algae that grows on my rocks looks pretty nice!
that is my main problem with most freshwater systems I do, I can't bring myself to set up a pink gravel spongebob house tank, so I go out and buy fluvals new plant light, and seachems nutrient gravel. Then it all just turns into a slimy noxious algae mess.
I now only do 10 gallon and under freshwater, because I still enjoy that densely planted forest look, but when it comes time to clean every few days it isn't such a chore. and of course frameless low iron panoramic viewing tanks are cheaper
oh but I forgot to mention I do understock my saltwater tanks, like a lot. My smallest one right now, a 20 gallon has two small clownfish and a candy cane cleaner shrimp.
I don't do much coral, just stuff like zoas and gsp, but I do enjoy macroalgae, if you get the right stuff it is hard to kill, looks nice, and grows fast!