You don't need a sump for a reef. But you will need to look into a protein skimmer, and lighting that is capable of supporting corals (T5, LED, or Metal Halide)
The canister filter can be used for running carbon or other chemical media, but should not be relied upon as a main source of filtration for saltwater, that will be your live rock and a protein skimmer
I would also look into an additional powerhead, you want 20x-40x turnover in water movement in your tank an hour - so a single powerhead rated for a 25 gallon tank will not be sufficient
With that said, I think you're okay with the tufa rock as live rock, but I will let others chime in on that.
And I will also second the comment that your tank is way, way too small for a panther grouper