closed loop

[marinelife]

I am working on designing a closed loop for my tank.

The inputs will be on the end because it has a cabinet. So question is do I go 2 drains or 1 drain.
Option 1 - a 3" input thru a valve then reduced to 2" to go into the pump.
Option 2 - 2 2" inputs, right out of the bulkhead would be a 3" pipe from each T'd together down thru a valve then reduced to a 2" pipe before entering the pump.
Option 3 - 2 1.5" inputs, right out of the bulkhead would be a 3" pipe from each T'd together down thru a valve then reduced to a 2" pipe before entering the pump.
Return pump will be a Red Dragon 230W Pump.
The input(s) will be half way down the tank wall and the returns will come in from the top.
I only have about 1 foot from the middle of the tank to the shelf the pump will sit on.

Which would be best or is there another option that is better. This is going on a tank that has been running for years with powerheads that are gonna need replaced.

[Subsea]

I suggest option 2.

[Klaus777]

is the intake 2.5" in this pump? If it is, then none of your options are ideal. As a rule of thumb, the intake of a pump should never be reduced directly at the intake. this can cause cavitation and turbulence which will put additional stresses on the impeller and shaft and can cause the pump to fail prematurely. It will also cause noise. The intake pipe should be 10 pipe diameters long (so 25" ideally) of the intake diameter (2.5") of a straight run before the intake to eliminate this.
In this case I would say to use 2 - 2" pipes out of the bulkheads, T'd to 2.5" pipe into the pump with as long of a straight run to the intake as possible.

[marinelife]

The pumps input is 2"
I was told by the sales rep to reduce it right at the pump
I am thinking 2 2" bulkheads t'd together with 2" pipe to the pump

[Klaus777]

The pumps input is 2"
I was told by the sales rep to reduce it right at the pump
I am thinking 2 2" bulkheads t'd together with 2" pipe to the pump


Just checking on the intake and output of the pump. unless I'm looking at a different pump:

http://www.aquariumspecialty.com/royal-exclusiv-red-dragon-3-speedy-230-watt-20-5m-10v-connection

I believe this is what you're looking at yes? nice pump BTW.

intake is 2.5" and output is 2". there is a difference when relating pipe sizes.

I'm just saying be sure first. A sales rep is not an engineer. I am, and I've seen things go wrong many times before they go right.

[marinelife]

A member here that I know and have helped with his tank build has the pump and it is only a 2" input, on the 230W Red Dragon as you linked too.
I have questioned why it says 2.5" on most sites.

I have never put a long run in front of a pump before. That is something I will have to look into seeing if I have the room for.
I can just go all 2" pipes from the bulkheads to the pump.