Hi there and welcome to Fishlore!! I assume by CT you mean cape town SA?
You could maybe get a resun sp1100 or better still 1200 L/P, i find them great in my fresh water tanks. Its always better to get a filter slightly bigger.

I'm not very well equipped with oscar knowledge but i think a 55gal is minimum for them tho they'd be much better off with a bigger tank. Stilll you'l find lots pf oscar fans here!
Glad you found this site helpful and goodluck with your setup!