Christy, if you were to go vertical and then tee of as Hillegom says, you would be getting at least 1700 gph flow out of the dart, that is taking into account one gate valve, one union coupling, 6" vertical, 8' horizontal, 6 elbows. This from the RC head loss calculator.

You know, I have no idea where I got it originally but I have seen it perpetuated throughout various forums. Is this not the case??

Oh cool. I still don't get the reason for the gate valve?? Dumb it down for me :razz:

got it from me. 1 90 elbow puts an extra foot's worth of head into a circuit. Or close enough to calculate for our needs.

Of course now that I try to find where I got that from, I can't, and find other sites that tell me 4ft for a 90 at 1" ID...sigh :)

Yeah that's not even close to being accurate. First it depends on water level height difference, flow rate, pipe diameter and pipe length but if you really wanted to estimate it would be closer to 3 elbows to create one foot of pressure provided the correct pipe size is used. The bigger the pipe diameter the less impact elbows have on head pressure.

The gate valve enables you to match the water being pumped back to the tank with the water draining into the sump. And if you have a gate valve on the drain line as well, it makes it easy to turn off the drain water for whatever reason: repairs, feeding, etc.

Got it! Thanks :biggrin:

Also by using the gate valve you can set your return flow to whatever you want.If you find the flow is too much from the pump just close the valve until you get it where you want it. Sequence pumps actually run quieter and last longer when under less load.

From the Reef Aquarium, by delbeek and Sprung vol 3 2005
Page 111 table 3.4
For every 1.5 in 90 deg elbow The extra resistance in thermoplastic pipe in feet is like adding 4 extra feet of pipe.
Let me restate
Adding a 90 deg elbow into 1.5 in pipe increases the resistance of the water as if you added 4 more feet of pipe.
How much resistance equivalent to feet of head, depends on the volume or g/hr you are pushing with the pump

So what you are saying is that a pump that pushes less volume will have less loss in a 90 degree elbow, all other things being the same? ie: A 1000 gph pump pushing water through a 1.5" 90 degree elbow will incur less losses than a 2000 gph pump?

For some reason that seems right, relating to some reading on fluid dynamics I've done... Can't remember exactly, but there's some sort of mathematical equation for that sort of thing... I don't have the book anymore, either, can anyone clarify this?

Anyhow, I would go ahead and use spaflex, just to avoid all of this... you will still incur some loss but 90 degree elbows are really really bad for friction losses because of the turbulence in the sharp corner of the bend.

+1 on using gate valves, and having some back pressure on the pump will not only make it run quieter but (I may have read somewhere) may make it consume less power.