Haha the only way I know how to is to get an adjustable air pump valve thing...Not sure what its called exactly but it allows you to slow down the air going to the filter. If its a filter with a built-in pump, I have no idea
I just discovered Aurora might be a Delta! His tail isn't drooping much and it does kinda look like guppy tail. Maybe a cross of an VT and a Delta? Don't know.... I hope he is!