Filter?

Ahhh, the wonderful uses of skimmate.

A sump "neatens" things up a lot, and makes the aquarium more stable. The more water volume, the more stable your salinity, temp, and other params are going to be, or at least the tank will take longer for problems to develop. A sump is extra water all around. For example, we have a 46 gallon bowfront. Our sump has about 8 gallons of water in it. This brings our total water level up to 54 or 55 gallons, which is much easier to handle.

Added bonuses with sumps that go along with "neatening" up the tank, is that your heater, skimmer, and other tank doodads can go in it instead of looking ugly and mad scientist style in your main tank. You also add your top off water to your sump, instead of to the main tank, so your main tank always has the same water level. And the pump from the sump is like a 3rd powerhead in our tank (at least in our setup ).

So essentially a sump is just to ease things up a bit and make the tank more tidy. But they also have added filtration from a biomedia or plants that help get rid of nitrates in a fuge setup.

But there are also hang on back fuges that are really helpful, and you can keep all the biomedia you need in your main tank in the form of live rock/substrate.

With canister or hang on back filters, there's added routine maintenance such as cleaning and changing filter pads, along with a less total water volume, and your heater and protein skimmer will be visible.

It all depends on the person and what they need. Simple sumps can be made from a 10 gallon aquarium, an overflow box, and a return pump. But others may find that they enjoy and feel better with canister or HOB filters instead of having to deal with the plumbing and safety features of a sump.

My advice is research research research and you'll be able to match yourself to what your setup will need. Another thing, living without a skimmer is like living without electricity. It can be done, but it makes life soooo much easier. Don't hold back on your wallet when selecting a skimmer, the more you spend up front the less you'll spend in the long wrong. You won't need as much Advil either, so that saves a few bucks.