Here's what I got back from Remora. I just copy and pasted the relevant part.
"Thanks for the message, I can help you out. We don't normally recommend upgrading pumps with the Remora, as larger pumps tend to overpower the skimmer, resulting in a very wet foam and increased bubble return to the tank. Upgrading pumps also involves switching intake barb fittings with one intended for the Remora Pro - this modification technically voids the warranty. However, if you'd like to try it, I can send you the appropriate fitting. Remember to be extremely careful when removing and replacing the barb fittings, as stress on the arm can crack the plastic. We've had quite a few customers try such an upgrade, with mixed results."
So from this answer it looks like I need to buy a bigger one of some sort.