I am setting up my first sal****er tank. (converted from freshwater)

It is 38 gal

I have 3/4 of the tank with undergravel filter with crushed coral on
top. Using a 145 gph power head

I also have an emperor 280 hang on filter.
I think this is 280 gph ??

I also have a large protein skimmer for a 90gal tank.

I plan on small fish, and hopefully some live rock.