40 Gallon Saltwater with canister options

[jyabs7]

Pretty new into the hobby but...i'm building up my 75 gallon freshwater and have a ton of spare tanks and a few filters that i'm looking into future options with while i let everything settle in on the current tank.

I know it's a very back and fourth topic, but one of the ideas is using my 40 gallon breeder or my 55 for a simple saltwater tank. I know next to nothing about saltwater but i'm reading and reading. I know sump's are preferred, but i also prefer not to drill a brand new tank when the closet retail is a few hundred miles away. If I kept the tank lightly stocked, went with live rock and sand, and pulled the bio media out of an fx6 (as to use it as strictly mechanical filtration), what major cons would i be facing? The FX6 is very capable for mechanical filtration, and the amount of flow it would provide in either of those tanks should be more than sufficient IMO especially if used with a spray bar. What concerns could I be looking at?

 

[Gourami Swami]

it's definitely possible to run a saltwater tank on a canister filter, many people have done it. It is less advantageous than a sump however. In a sump you can put other equipment like protein skimmers or media reactors, as well as have a refugium to grow macroalgae and as a safe place for healthy pods. This ends up being a great benefit and makes the setup look nicer since heaters etc can all go in the sump.

You can have a sump without drilling your tank as well, there are hang on back overflows which can be used on standard tanks. As for being enough flow, it depends on what kind of saltwater setup you do. For a fish only setup the flow wont matter as much, for a reef tank you may want additional powerheads.