Need a small water pump

SprigOfTheLivingDead

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As I said in my auger thread I now need to figure out a pump for my irrigation line but I have no idea what I need to get. So, if anyone has some knowledge on water pumps I would love to hear it. To help with that I drew a diagram of what will essentially be my setup and numbered a few points of note.

I was instructed that for a line of 150 trees I would need 8GPM at a min of 35psi & some 3/4" tubing can do 10GPM.

water tank diag.jpg
Tank = 550gal water tank with a 2" exit hold off of it.
green circles = trees
black lines = 3/4 tubing
1 = shut off valve
2 = filter
3 = water pump (electric)
4 = pressure regulator (I was told to put this right after the pump)
5 = 1/4 lines with a 3.2GPH spray stake

Questions
  1. The tank will have a 2" exit hole that I will need to reduce this to 3/4" either at the tank exit, right after the shutoff (1) or after the pump (2). So if you have thoughts on when that should be speak up.
  2. Is there some algorithm I need to follow up calculate the horsepower I need from a pump in this situation?
  3. What pump could I use in-line to get the pressure up to that 10 GPM pressure? Additional thought: I suppose I could toss a pump inside the tank itself and have it push a line out the 2" hole and just seal that up so there's just a hose running out instead of a 2" --> 3/4" reducer.
  4. What else do I need to be thinking about that I have no idea of?
 
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Dirtmechanic

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35 psi is not much. It seems like the head weight of 5 gallons in a pipe vertically would weigh that much. Are you sure you need a pump?
 

SprigOfTheLivingDead

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35 psi is not much. It seems like the head weight of 5 gallons in a pipe vertically would weigh that much. Are you sure you need a pump?
I have no idea. I just assumed I'd need to put a pump in there.

I've helped build some gravel beds for raising trees and it was found that you had to elevate the water tank by a good 10-12 feet over the bed in order to create enough pressure on the the soaker hose so I figured this would be an amplified situation since my 3/4 hose will be 400' long
 
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SprigOfTheLivingDead

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I should note that the water tank will sit at the top of a small grade. I wish I could give you the angle but it's currently 3 degrees outside, so I'm not going to go setup my survey equipment my father gave me to measure it out ;)
 

Dirtmechanic

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I have no idea. I just assumed I'd need toto put a pump in there.

I've helped build some gravel beds for raising trees and it was found that you had to elevate the water tank by a good 10-12 feet over the bed in order to create enough pressure on the the soaker hose so I figured this would be an amplified situation since my 3/4 hose will be 400' long
The weight of water in that pipe is gonna be over 400 lbs. About a gallon every 98 inches if my math is right So now you need a bit more because of friction to I guess. But the weight of 550 gallons is stout. Same idea as the way they feed the houses with those big water tanks. I am just curious if you really need a pump.
 

SprigOfTheLivingDead

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The weight of water in that pipe is gonna be over 400 lbs. About a gallon every 98 inches if my math is right So now you need a bit more because of friction to I guess. But the weight of 550 gallons is stout. Same idea as the way they feed the houses with those big water tanks. I am just curious if you really need a pump.

Huh. That's a really good thought. Maybe I should first get all the holes drilled, the irrigation pipe in place, the drippers in place and then test put that pressure prior to purchasing a pump I might not need
 

Dirtmechanic

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Huh. That's a really good thought. Maybe I should first get all the holes drilled, the irrigation pipe in place, the drippers in place and then test put that pressure prior to purchasing a pump I might not need

I could see a water column pusher. How does the big tank get filled?
 
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