dart pump question
 

ok so I'm looking at the reeflo dart for a return pump. Thing is I'll have at least 6ft of pipe from pump to the sea swirl I'd like to attach it to, also there will be at least 8 elbows involved with this (2 sea swirls). If each elbow equals 1ft of head that makes 14 feet of head. The pump shuts off at 12'. So this won't work will it?

Another thought, if I use that flex hose there won't be any elbows, will that work better?

You will have a more sweeping turn with flex hose than with a 90. Definately will be less friction. All you need to do is eliminate 2 elbows and then be just at the max head.
I think getting rid of 8 elbows would do that for you if not more. Must be a chart for that somewhere

First, it is 12' of "head" that the pump stops working at, NOT 12' of pipe, and the frictional losses depend heavily on the pipe size. 1.5" pipe is more than enough for a dart.
Second, are you counting each output elbow of the sea swirl as a inline elbow. You should be counting each elbow in the "path" to the tank.

IE: if your return splits into 8 lines and each has an elbow, you really only have 1 elbow between the pump and the tank.

BTW: I had a dart, and now a snapper and I do love those pumps.

Ok, I thought the 6 feet of pipe to the sea swirl was vertical

The Darts aren't considered hi pressure so will roll off pretty good with head.

I was trading some e-mails last year with reeflo about using a Dart with 15' total head (was about 9' vert, 9' horiz, plus fittings), didn't get an exact answer but got the impression would be flowing near zero.

Suggest running your numbers on RC Head Loss calculator.

the 6' is vertical but by the time it comes out of the pump and then goes up and tees off to each sea swirl theres a whole lotta elbows.

wow this was like another language to me. the return was basically splitting into two lines each having a crapload of elbows. Heres an artistic rendition of what I'm talking about. Yes I know my talent is pretty impressive :wink:

http://i23.photobucket.com/albums/b3...elbowmania.jpg


I will be using 1.5" pipe, I'm thinking spa flex will likely be the way to go anyways as hillegom mentioned, there will be less friction. As for the elbows that are actually part of the sea swirl, I had totally forgotten about those.

Thanks for the help guys, keep it going if you have any other suggestions! I've been living in submersible mag pump land for the past 5 years, its as far as I can think :razz:

Christy, I would suggest a gate valve between the sump and the pump and another on the return line. Very handy for setting your flow just how you want it.

EDIT: That should read a gate valve on the drain line and one on the return line. You don't need one between the sump and the pump.

Your artist's impression is good.
Would you be able to go all the way vertical and then tee, and then go straight into each sea swirl?

Where did you get that 1 elbow equals one foot of head pressure?

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.

My setup is similar ~1700gph
 

I just pulled my dart and replaced it with a snapper. But my setup is close to what you are planning, but without the sea swirls. I would recommend going with 1.5" spaflex (what I have) as it will give you a bit better flow. I get about 1500-1700 gph out of the dart going up 6ft to the tank with 2- 45's,3 90's and gate value and a swing check in there.



Oversize pipe also makes it a whole lot easier if you want to ever upgrade pump. Just swap out the pump and go. Even better with the dart and snapper becuase the arfe the same wet end. Just undo one, and put the other in place. :)

Anyway, you'll get pretty good flow out of the dart. and a BIG +1 on the gatge valves -- I put one before and after the pump with a union to be able to remove the pump for service without draining the sump.

Christy your Dart can handle it. I always prefer, if space permits, a valve and then a union between the sump and return pump and then a union and then a valve coming out. This makes pump replacement a snap and allows you to control flow on the return. I don't feel it's necessary to drain the sump to change a pump.:wink: