How big to drill hole in overflow?

[fish head]

I am in the process of having a 240gal tank built. I need to know what size to drill the return hole in this display tank. Meaning the RETURN hole in my display tank, from my sump in basement (approx 14 feet).
I was considering making this hole 2.5", to accommodate a standard 2" return hose. A friend suggested I go even larger, as a larger return line mean less head pressure on the return pump. Even though the return Iwalki 100 RLT (my next purchase) pump outlet is only 1.5" diameter, he says it be better to go larger diameter hose. How large would you suggest for the return hose/hole?
Obviously, I want to get the most volume out of the return pump at a height of about 14 feet.
Thanks for the help,
Greg

 

[rangermonroe]

If you are having this instaled... why the ???. Why are you worrying about the DIY part?
Is your installer lacking a 2.5" drill?

 

[stacyt]

I don't think you'll gain much benefit from going with the larger return. I tried that on my return, and it really seem to lack good pressure. I changed the setup back to match the return pump, and got a much better flow back into the tank.
As for your question I qould recommend buying the bulkhead, and then measuring it to see what size hole to drill. Not all bulkheads require the same size hole.

 

[fish head]

Guess I should clarify the question.
Will an Iwalki 100RLT pump push out more water at 14 feet if it is plumbed with 3" hose or smaller 1" hose?

 

[stacyt]

I founs this info on another site, and a couple of catalogs. May help answer your question. I think you may need to look at another pump. Especialy if your goin 14'.
The RXLT type pumps are best suited for circulation only, where water encounters very little back pressure such as returning water from a wet/dry sump. Excellent where a high turn-over rate is desired! All Iwaki pumps run extremely quietly and are saltwater safe!

 

[fish head]

The Iwalki RLT is differerent from the XLT. Yes the XLT says it is for circulation but the 100RLT is designed for high head pressure.
Would I be better of plubing with 3" rather then 1"? Do you have the web site that explains this? I'm sure there must be a formula. Any rocket scientists out there?

 

[adam13]

Hypothetically speaking, you will get the same ammount of return volume regardless of the size of the tubing. However.in the real world, your pump will not pump as much volume if the pressure on the outgoing side is greater than on the incoming side. So bigger area equals less pressure, yes. But running tubing that far, even with large tube will slow the flow rate a lot. Possibly look into two return pumps if one doesnt produce the flow you want. The return from the tank to the wet dry will definately pull a lot of water due to that height difference. Good luck,
Adam

 

[zafirablanca]

I don't know exactly how to help you except to tell you to try and get some feedback from one of these guys:
Broomer - has technical answers for technical questions
Bang Guy - has a HUGE refugium in his garage (or basement?). He built it himself, so he probably has been there with the plumbing dilemnas.
MelbourneFL - just finished a rather large plumbing project that he got alot of feedback for here
Try a forum search on things like 'head pressure' or 'pipe diameter'. You will get some of the good previous threads that discussed these things in detail.
Good Luck
-Christine

 

[broomer5]

Fish Head
I'll toss in some things to consider.
Head pressure is head pressure ~ what I mean is the "pressure" exerted at the return pump will be exactly the same whether you use a 1" return line, 2" return line or 12 in diameter pipe for the return line.
It will be 14 feet of head ~ or 168 inches of water pressure ~ or roughly 6.06 psig @ the pump.
So ........ what does this mean to us.
The larger the return line means the slower the velocity or speed of the water as it moves up and into your display tank.
Using smaller returns means an increased turbulant flow profile, possibly more friction, and in theory, less flowrate .... but the water moves at a much faster rate ( feet per second ) and therefore will create more internal tank circulation.
It will shoot out farther and faster through a spraybar or jet fitting into the tank. This is good if you want to provide a lot of "intank-circulation"
Using a larger diameter return line - you'll have more laminar flow, less friction loss, and in theory - you'll have more flow, but it will be moving at a slower rate or velocity. It will dump water into the tank at a slower feet per second rate - but the volume would be the same as Adam13 mentioned.
Good for moving water through the tank - but would not create near as much "intank-circulation" as a smaller return line.
A 1" diameter pipe extended vertically 140 feet in the air - filled with water will create about 60 psig of water pressure as measured at the bottom of this vertical column of water.
A water tower 140 feet tall and 20 feet across ( diameter ) will also create the same 60 psig of water pressure.
So the head pressure is the same for both.
You don't gain pressure by increasing width - only height.
Sizing your return pump - you should consider not only head pressure to overcome from the basement/display tank distance ~ but also at what "rate" or speed you want this water to move into the tank.
Does this make sense ??

 

[fish head]

That is an excellent explanation!!! I will plumb for a 2" pipe and adjust the outlet hole size to accomidate the desired spray. Most likely I will T off at the top, so I can have water circulation out of two pipes in two different directions. Two 1" spray bars being fed off the 2" pipe.
Thank You,
Greg