Plumbing advice needed - closed loop system

[LowCel]

I am going to start the plumbing for a closed loop this evening so I wanted some help deciding which way to go for the return lines. Going from the tank to the pump (Reeflo Blackfin 3600) I will have two 1.5" diy pvc overflows going to 2" then into the pump.

My question is which route would be best going back to the tank. The output on the pump is 1.5". Here are my two options. Also keep in mind I will be going around the sides of the tank since I wasn't smart enough to leave enough room for plumbing behind the tank. However, the way the tank is the plumbing will barely be visible.

 

[js302]

this is like that "lamps in series vs lamps in parallel" question!

I think that in fluid mechanics, pressure is exerted equally in all directions which i think favours set-up 1 if your pump is strong enough to maintain pressure in the pipes as long as the outlet spaces back to the tank are not too big.

Set up 2 may favor one route back to the tank over another unless your plumbing in incredibly symmetrical.

Go for set up 1 but don't let outlet holes get too big!

 

[LowCel]

The pump is going to have too much power so I am going to be using ball valves to limit the gph's so that is really not too big of a concern.

 

[Pharaoh]

I would go with #2, but I agree to keep the lines as small as possible. I lost a lot of pressure running 1" lines with my reeflow. Probably due to the distance required. I should have used 3/4".

 

[LowCel]

Thank you.

I forgot to ask, what size should I make the diy overflow (s) with? Would I be able to get by with one 1.5" overflow or would I need two of them? I would like to be able to get by with one overflow, since this is a closed loop it seems like that may be possible but I really don't know.

This is the type of overflow I am going to use. This picture is from www.melevsreef.com.

 

[Pharaoh]

I would say that you will need two overflows, but I am not exactly familiar with that type of overflow system. Are you not planning on using this to filter?

 

[LowCel]

No, this is not going to be filtering. It is just a closed loop for the undergravel jet system. I have a 75 gallon wet/dry attached to a reeflo dart to take care of filtering.

 

[Jgray152]

I don't see how that is an overflow system.(pictured) I hope that PVC stack with the cap is going to stay capped in that picture. Otherwise that will never work.

To get mroe equal flow through each jet, I would go with your second design. I havn't checked to make sure the size piping would work be the design should.

The first design takes after a spray bar. A spray bar which has a lot of pressure behind it will have a high velocity of flow coming out the far end and less toward the beginning of the output. Its different when there is no pressure and water falls through the holes at the beginning and less toward the end.
(If no one believes me, I can take a video of a rena spray bar with this effect)

I believe this is because the water is flowing with a higher velocity past the beginning sets of holes so there is LESS pressure where as once the water flow hit the end of the spray bar, pressure INCREASES causing a higher velocity of flow at the end of the spray bar instead of the beginning.

To test this theory, you can even create a spray bar with an open end, turn the water on and watch how very little water falls falls through the holes, start to put your thumb over the other end (not entirly) and you will see the holes at the far end will be flowing more than the holes at the beginning.

 

[LowCel]

The picture is actually a complete closed loop system. I was only making reference to the overflow portion though. The pieces with all of the holes drilled in it is actually the overflow or what ever it should be called.

Just for the heck of it check out his site at www.melevsreef.com, you will be amazed. He really knows what he is doing.

What you are saying definitely makes sense about the return though. I will be going with option number 2.

 

[Pharaoh]

No, this is not going to be filtering. It is just a closed loop for the undergravel jet system. I have a 75 gallon wet/dry attached to a reeflo dart to take care of filtering.

Well, with a closed-loop circulation system, you should be fine with one overflow as long as the system is sealed and there are no leaks. Should work just fine.