Hooking up an external pump

[crashinc25]

I understand the above dispute over the fitting sizes, but I have the right fittings for the right sizes already. It is everything AFTER the union that becomes a problem. Since I am going to run the return lines back through the overflow, how to get a get the "fresh" water into the tank and not in the overflow itself? There are no holes and the overflow goes to the top of the tank. Seems counter productive to return filtered water to the dirty water intake.

 

[CHOMPERS]

...Since I am going to run the return lines back through the overflow, how to get a get the "fresh" water into the tank and not in the overflow itself? There are no holes and the overflow goes to the top of the tank. Seems counter productive to return filtered water to the dirty water intake.

The way it is done results in a loss in efficiency. The riser is hidden inside the overflow and it carries the water over the top edge of the overflow. The overflow should draw surface water and floating debris to it (by it breaking the surface tension). By having the return coming out of the overflow, the return current takes some of the debris out of the incoming current and returns it to the tank. (But in the end, everything still gets filtered.)

You can be creative and set it up however you want. You can return all of the water to one overflow and draw from the other. You can also drill a hole in the side of the overflows near the top and add another bulkhead in each. Then plumb to that and on the tank side, add a return nozzle.

 

[CHOMPERS]

Oh, one more thing... You can draw from all four holes and then return the water over the edge. I don't like external plumbing though.