Question about pumps

[BEB]

I am designing my own homemade tank (will likely buy the plans off this site as well, just for reference) and one question I have is about pumps. How big (GPM) are most of the pumps in commericial tanks? I have heard magnetic pumps are best (to avoid impeller shaft corrosion), but the ones I have looked at are $350-$500 for 40-65 GPM (1/2 to 3/4 HP). I want to get one big enough to insure of adequate flow and filtration

Once I start building the tank, I'll post a link with pictures, specs, etc....

thanks,

-beb

[This message has been edited by BEB (edited 12-15-2003).]