I use Jebo fans. They are cheap, so when they get all gummed up with salt creep a person doesn't get too excited about it.
They come in 2, 4, and 6 fan. Move lots of air. Really good buy imo. My canopy is open in the back and the fans are clipped on the back rim and blow down on the water. I can feel the air movement coming out the top of the front of the canopy. One 4-fan makes a 3 degree difference on my tank. The Jebo fans can be taken right apart to clean too.
