I am going to use a 1200gph mag pump for my return pump to 90 gal dt. Pump has a 3/4 in threaded male nipple. I have about five ft head pressure. Should I just use 3/4 in pipe into dt or will I get better gph flow if I put a 3/4 to one in adapter and then plumb one inch pipe into dt? Thanks
What size return pipe should I use?
- Thread starter antjtc
- Start date
slenhart1018
New member
You will get more flow out of the 1" for sure. How will you be controlling your flow? I assume you are adding a ball valve somewhere? On the drain side? On the return side?
FishNFun
New member
With Mag pumps it's recommended to have the pipe twice the size of the outlet so 1.5" and then reduce at the tank. I run a Mag 9 that way and it's been running for almost three years without a problem and is very quiet. I reduce it down to 1/2" locline as it enters the tank. I also use a true union valve to control the flow and make it easy to service the pump.
Ron Reefman
Active member
I don't think so. The flow has to past thru a 3/4" outlet at the pump. So 3/4" pipe or 1" pipe doesn't really make any difference. The bigger pipe only reduces the speed the water moves thru the pipe at, it doesn't increase the flow from a pump. The 3/4" restriction at the pump is the limiting factor. If you could remove the 3/4" restriction and have all 1" pipe, yes, you might get more flow.
I assume this is a return from the sump to the DT. Add a valve (ball or gate) on the output side of the pump and if you are using pvc pipe, add unions on either side of the pump so you can remove it when you need to clean it or service it.
+1 to what Ron said.
I run a Mag 18 in my sump and I use a 3/4" return line all up to the tank and then 3/4" loc line in the tank. I have an overflow rated at 1500 gph and the overflow maker recommended a 3/4" return line. (I have about 9' head so the Mag 18 only flows around 900-1000gph at that head distance)
Ron Reefman
Active member
Think about it this way. The pump is rated at 1200gph. If you could get more flow with a bigger pipe added on after the 3/4" pump outlet, it would flow 1500gph, heck, add an 1.5" pipe and get 2000gph... why buy a bigger pump, just add a bigger pipe. Sorry, it doesn't work that way.
symon_say
New member
Bigger pipes only slow down the speed of the fluid, if a pump puts about 1200gph it will put 1200gph with a 1.5", 1", 3/4" or 1/4" the difference will be the speed of the fluid in the pipe that some people call pressure 
, (in a restricless world).
In real world bigger pipes will make flow less restricted giving you less pressure loss, but be careful if the pipe is big enough pump might not have enough power to get the water to the tank.
, (in a restricless world).In real world bigger pipes will make flow less restricted giving you less pressure loss, but be careful if the pipe is big enough pump might not have enough power to get the water to the tank.
cordell
New member
Not stepping on any toes here... I don't think anybody is trying to get MORE than 1200gph from the pump, but just getting 1200gph from the pump is the issue. People buy a pump rated for a certain volume of water pumped and should plumb those pumps as the manuf. suggests to get that flow.
I ran my mag 9.5 for years with 3/4" pipe with no problems, having to restrict it just a little because overflow couldn't keep up. A couple weeks ago I changed over to 1" pipe and have to restrict the flow more (judging by how much the valve is closed) because of the overflow keeping up, and that's even with adding 2 reactors. Take that with a grain of salt...
I believe the advantage of going with larger pipe is by reducing the friction of the pipe over the entire run of the pipe and through all of the fittings such as elbows and Tees. 1.5" pipe will give less friction, therefore less restriction, than a 3/4" pipe.
Mag says on the instructions to use no less than 1.5" pipe. According to the head loss calculator (stolen from another post):
Mag 9
5ft, 1 90*, 1 45*
no valves
Using the calculator....
.75" diameter: 616gph
1": 705
1.25": 746
1.5": 755
2": 762
2.5": 764
3": 765
Almost 150gph increase from 3/4" to 1.5" pipe. If that little (or much) flow is a big deal, then 1.5" is a good choice.
Just something to keep in mind... I once thought too that if the outlet was 3/4", larger pipe would be a waste, but through researching for my own setup, I learned that isn't necessarily true.
Also "borrowed" from another post... read the text below the image.
I ran my mag 9.5 for years with 3/4" pipe with no problems, having to restrict it just a little because overflow couldn't keep up. A couple weeks ago I changed over to 1" pipe and have to restrict the flow more (judging by how much the valve is closed) because of the overflow keeping up, and that's even with adding 2 reactors. Take that with a grain of salt...
I believe the advantage of going with larger pipe is by reducing the friction of the pipe over the entire run of the pipe and through all of the fittings such as elbows and Tees. 1.5" pipe will give less friction, therefore less restriction, than a 3/4" pipe.
Mag says on the instructions to use no less than 1.5" pipe. According to the head loss calculator (stolen from another post):
Mag 9
5ft, 1 90*, 1 45*
no valves
Using the calculator....
.75" diameter: 616gph
1": 705
1.25": 746
1.5": 755
2": 762
2.5": 764
3": 765
Almost 150gph increase from 3/4" to 1.5" pipe. If that little (or much) flow is a big deal, then 1.5" is a good choice.
Just something to keep in mind... I once thought too that if the outlet was 3/4", larger pipe would be a waste, but through researching for my own setup, I learned that isn't necessarily true.
Also "borrowed" from another post... read the text below the image.
Ron Reefman
Active member
symon_say: Bigger pipe will not reduce pressure, it may reduce friction loss against the sides of the pipe, but that would be minimal at best. Whatever the pump is pushing in psi, it is pushing against all the water in the pipe. Once the bigger pipe is full, it acts the same as a 3/4" pipe in flow (gph) and pressure (psi).
TeHGuy: More water in the bigger pipe doesn't effect the head pressure. It is only the weight of the water that is directly above the 3/4" outlet of the pump. If all the extra water added to the head pressure, when you dive in the ocean the weight of all the water in the ocean would be pushing down on you, but it doesn't work that way. Only the water that is directly above you adds to the pressure. It is directly related to the height and not at all to the diameter of the pipe.
TeHGuy: More water in the bigger pipe doesn't effect the head pressure. It is only the weight of the water that is directly above the 3/4" outlet of the pump. If all the extra water added to the head pressure, when you dive in the ocean the weight of all the water in the ocean would be pushing down on you, but it doesn't work that way. Only the water that is directly above you adds to the pressure. It is directly related to the height and not at all to the diameter of the pipe.
You need to find the balance. There is a lot to take into vonsideration. If you overuse the PVC going straight up the your also adding more water in that line. More water equals more weight. Increasing head line pressure. That could decrease flow more than undersized pipe if you go to big. It makes sence to use pine with the same I.D. as the outlet of the pump. Just make sure all your fittings match the I.D. Of the outlet. Some get on the small side.
at 1200 gph i would stick to 3/4".
here is a link that shows different pvc sizes and flow rates with no pressure, minimium pressure and high pressure.
http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml
here is a link that shows different pvc sizes and flow rates with no pressure, minimium pressure and high pressure.
http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml
BigCountry74
New member
90g? 3/4 for sure. X2
TeHGuy: More water in the bigger pipe doesn't effect the head pressure. It is only the weight of the water that is directly above the 3/4" outlet of the pump. If all the extra water added to the head pressure, when you dive in the ocean the weight of all the water in the ocean would be pushing down on you, but it doesn't work that way. Only the water that is directly above you adds to the pressure. It is directly related to the height and not at all to the diameter of the pipe.[/QUOTE]
I disagree. Not with your out in the ocean comment, your right on there. But with the fact that the pipe has fitting changing the size of the pipe. This adds a taper down to the outlet nozzle of the pump. The inherent taper in the fitting also directs the weight to a focused point. If the plumbing was a cylinder with a flat bottom and a fitting in the middle then the open ocean analogy would apply but seeing how plumbing fitting are tapered all the weight of the water is focused down into the pump.
I disagree. Not with your out in the ocean comment, your right on there. But with the fact that the pipe has fitting changing the size of the pipe. This adds a taper down to the outlet nozzle of the pump. The inherent taper in the fitting also directs the weight to a focused point. If the plumbing was a cylinder with a flat bottom and a fitting in the middle then the open ocean analogy would apply but seeing how plumbing fitting are tapered all the weight of the water is focused down into the pump.
Utah Fatman
New member
For a given velocity each size pipe has a friction loss factor for foot of run (and another factor for each fitting). At a specific velocity the larger pipe will have less friction loss. Moving 50 gallons per minute through a 3/4 inch pipe will require more pressure since it has to travel faster and therefore has more friction loss than water traveling at a slower speed. Moving 50 gallons per minute through an 1.5 inch pipe lets the water travel slower and has less friction loss. The 3/4 outlet on the pump is another fitting that created friction loss in the system. Just accept it and move to a larger pipe, which equals less velocity to hit at the top of the tank in the return. Hope this makes sense.
Makes good sense. I think we are looking a little to deep into this. My lines are 3/4" my pump outlet is 1/2. I went a little bigger and it quieted down the pump. If we were pumping water 20-30 feet then yes we should make an issue of it. In my honest opinion that flow chart posted earlyer looks like a great guidline. If your close to needing the next pipe up on the chart then step it up. That chart looks like straight line horizontal flow. If your adding several bends just go a little bigger.
Ron Reefman
Active member
Sorry, but the gph flow out of a cone is the same as the rate out of a pipe the same diameter as the opening in the bottom of the cone. The extra water 'tappered' toward the opening has no effect, no increased pressure. If what you are saying were true, all water towers would be cone shaped to increase the water pressure.
Thanks everyone for your helpful comments. I love this community, with everyone being so willing to offer helpful advice.
What is a loc line, and is there any advantage to using such a thing as opposed to simply putting my pvc line directly into the tank?
By the way, does anyone know of a type of paint I can use to paint my pvc line into the tank black (assuming if I don't switch to a loc line once I find out what that is)? I'm afraid if I use generic paint it will peel as time goes by. Thanks.
