20 gallons is a fine size for a tank. If all you're going to have is a couple clowns and some LR
then you have a little more leniency with water quality so a lot of equipment isn't a must (but does help if you have the option).
A 20 gallon with a DSB
and about 20-30 pounds of LR
will do just fine without the need of a whole lot more. A couple of 100 GPH
power heads to give you some turbulent water movement and thats all the "Tank" needs. You'll need some good test kits and a quality salt mix. If it's in your budget, I'd get a good light fixture. a FOWLR
doesn't need a lot of light, but IMO
the standard 20 watt NO
bulb that comes with a basic 20 gallon tank just won't show the true beauty of the clowns or the LR
. And the coraline and other fun stuff on the LR
will do better with a little stronger light as well.
As long as you maintain good habits for testing and topping off the water in your tank you should do just fine and there's really not much to make any noise.