The mp40's have a lot of flow, but it's so dispersed it doesn't feel like 3000 gph at 100%. I ran 1 mp40 on my 75g in-wall sps tank. Since I can view the tank from the back, I was able to see considerable flow behind the rocks when using short pulse mode. The back and forth action pretty much eliminated dead spots and there was a nice under current that kept particles suspended.