Filter For a FOWLR?

Substrate (unless you are going bare bottom) sand

Are you going to use a sump? If so overflow, sump, return pump, plumbing.

Are you planning on removing phosphates (nutrients from feeding fish) from your tank by water changes or looking for an HOB solution? You could run GFO and Carbon. Optional.

Reservoir for standby RO/DI water. Reservoir for Pre mixing saltwater.

Thought of an auto top off?
http://www.autotopoff.com/
YouTube

 

HOB skimmers are good. At one time I had 2 tanks set up using them. The issue I find is that generally, they dont skim the surface of the water. Without surface skimming, or adequate surface movement, you will develop a slick on the surface which will look ugly and smell. If you go HOB skimmer, be sure to put a powerhead at the top of your tank to churn up that film so the skimmer can get it out.

 

Thanks for reminding me of that stuff. And I probably will not be using a sump because my budget is quite small.