circulation help

[reefnewbie54321]

anyone want to give me a link to how a closed loop works/should be built or explain it to me. when i was running my tank i didnt want to drill so i used powerheads and melevs scwd circulation method but now that im making the stepup to a 100 gallon i dont think i want any powerheads in my tank but so far i literaly have found NOTHING on a closed loop circulation system through google and the serach on this site isnt working.

please help

[MCary]

A closed loop is just what it says. The loop is closed, by that I mean that the water enters the system below the water line and exits below the water line. Besides creating a flow where power heads are not visible it does something else that flow from your sump can't do.

Since the flow through your system is not closed, the sump becomes a separate system. The pump collects water from a reservoir (your sump) and pumps it up to the tank. Because of gravity and the fact that the pump must over come it, the output of the pump is lessened. This is called static head pressure. So a 1200 gph rated pump might be only 1000 gph at 4 feet and dramatically less as the height increases. It will eventually reach a maximum where it won't lift at all.

However, in a closed loop, since the intake is below the water line, the pressure from the water entering the system is the same as the pressure leaving it. So there is no static head loss. Just loss from friction. So a 1200 gph pump, delivers close to 1200 gph (minus friction pressure from pipe walls and elbows)

The main reason for a closed loop system is to maximize the efficiency of the pump used.

Did I make any sense?

Mike