i do not know how hard it is in relation to bigger tanks but I have a 10. Was my first saltwater tank ever and it is doing fine. I run a red sea prizm skimmer, moddified AC 50 as a fudge, and a Current USA Orbit 2x40 watt. I got by just fine without the skimmer as well, but the water quality seems to have improved and my algae problems are pretty much gone using it. I do weekly 10% water changes as well. I think you can do just fine with a 10 depending on the livestock you plan to keep.