[labatt]

I understand that, but Im still not clear on the thought. Look at it this way- you have X pump puming Y amount of water from container A to container B. The pumps rated flow is Y (adjust for head pressure if you like, it doesn't matter)You are moving Y amount of water in both containers so the total amount of water moved by the pump would be Y+Y. In the aquarium there aren't 2 seperate containers but you still have two ends of the pump so couldn't you sort of say that its actually moving Y+Y water? Or ever better worded the flow in the tank is Y+Y, since thats not how a pump is rated? I know its kind of retarded but it almost makes sence to me.