Size of Return Pump

I've read a few articles about reef tanks that suggest that the "ideal" size for a return pump should be a pump that pumps 5 times the total number of gallons in your tank and sump, and that you should rely on circulation pumps for the water flow in your tank, not on return pumps.  I'm going to be in the market to replace my return pump eventually and wanted to know if anyone here follows that advice?  I have an MP40 for flow, so not really looking to boost my flow via a return pump.

I use to do the 10xs rule until I read a article about it. If you think about it all your pump is for is to move water. It doesnt do any good to pump i high volume of water through your sump all the time. your skimmer can only handle so much water and your refuge can only export waste so fast. So why would you want to pay twice as much for electricity and the cost of the pump to do the same job a pump half the size would handle. Use your mp40 for movement but find a pump that will move 5xs your total tank volume and youll be fine!

I have a 65 and wil be using either a 650 or a 750 for the return....it as to move up liken 4ft to e enter the tank...I'll have 2 koralia 3 for circulation....would that be enough?

Viper, a Mag 7 at zero head is 700 GPH, at 4 feet it's 480; the mag 9.5 is 800 at 4 feet.  Both will be even less when you factor in friction loss across the lateral piping and any connections.  If you have a 65 and a 20 gallon sump minus what you have for rock and equipment you will do ok at 750 gph, that's about 10x per hour.

Fat