Drip Irrigation Pump Requirements

[MHHSP]

I'm trying to decide on the correct pump for my drip system. I have 20 plant sites (1 gal), using 3/4" feed line and 1/4" drip tubing with 1/2 gal/hour compensating emitters and about 6 feet of feed line. What kind of pump will I need for this system? I've hear I should be wanting a pressurized system 15-20 psi which I'm not achieving with a cheap submersible pump.

 

[Lazyman]

Don't use emitters, they just clog. Lots of threads on this subject though, like here https://www.icmag.com/ic/showthread.php?t=167241

 

[MHHSP]

thanks Lazyman I have read through that. OK say I go without emitters what size pump would you recommend without any, I don't want to much output and will water be able to reach all the drip line evenly?

 

[MHHSP]

So say I use a 265 gph pump with 20 plant sites 3/4" main line connected to 1/4" drip line (no emitters) 265/20=13.3 gal/2= 6.6 gallons delivered in 30 min. or .33 gallons per plant.
Sound right? Just worries about even flow rates.

 

[whadeezlrg]

hope you get some answers I really need to setup drippers over here.

 

[rives]

Without something to create back pressure and meter the flow you will definitely get uneven watering. The shortest lines will have the least resistance and that is where the water will go. How about the rainbird drip regulators for their drip systems? On my outside systems, I have only had one plug on me in several years of usage.

 

[MHHSP]

Wouldn't back pressure be created by the fact that the main line 3/4" is clamped off at the end, it seems once the pump is on, constant pressure is achieved after all the air is pushed out of the lines. Just doin some testing.

 

[solarz]

There's no science behind what i did (or at least i don't have any to justify this...), but from my past experience:
1. I got a 1/3hp pump from lowes (or possibly home depot) and fit this from 3/4" dryer tubing to 3/4" pvc piped in a square(this was my "manifold).
2. I had that attached to the ceiling 8ft high and secured for the weight of the water.
3. I drilled 1/4 holes into the pvc and shoved the 1/4 dripper hose into the pvc, NO GROMMETS! NO LEAKS!
4. I ran about 40 1/4 lines to the plants that was in a 8x8 enclosure. I used adjustable emitters, but they were the stakes that shot out like sprinkler heads. Got pretty even flow around plant base.
5. I pumped the water from a 50gal barrel up to the ceilings (8ft). The power behind the pump was more than enough to fill the 3/4" pvc allowing for even flow from the 40 emitters, to the plants on 3 different levels.

Hope this helps...

 

[MHHSP]

Thanks for the input, I went with no emitters just 1/4" out of 3/4" feed line, using either a 265 or 391 gph pump (i have both) will try for the first time tonight...

 

[rives]

I just got back to this and was wondering how it worked out for you. I would think that with (20) 1/4" lines hooked up, you would never pressurize the 3/4" line unless you had a pretty high input volume. The area of the 3/4" line is .442, and the combined area of the (20) 1/4" lines is .982, so it seems to me it would be like a soaker hose with the hose bib barely cracked - the water would all run out before it got to the end. Hope it worked for you, just interested to know how theory (at least mine!) worked with reality.

 

[MHHSP]

Double post... deleted

 

[MHHSP]

Alright I watered last night, not to my calculation, but it worked out none the less. Using a 265 pump the line pressurized in only a couple seconds (only a few feet of 3/4" line, maybe 8-9 feet total length including all splices and such, but each individual line about 4-5 feet from the end to the pump) the system seemed to work fine with 6.5 gallons reaching the 20 plants in about 1-2 min time.
Everything seemed to be even, all grow bags weighed about the same.
Happy with the results : ) even thought I didn't get a traditional drip system : (

 

[rives]

You must mean 6.5 gallons total, divided amongst the plants? That pump should do 4.4 gallons a minute so that must be the case. Glad to hear it worked for you!

 

[BenjaminSocks]

Did you put a cup at different points of your irrigation system to check how output varied?

Take an emitter point, and place it in a cup. Run the pump for 1 minute. Compare how much you collected. If some cups are twice as full as others you have a problem.