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Sizing a pump for Drip Irrigation - Can I use a 1.5 HP, 2" outlet

Posted by MattByc 9b (My Page) on
Mon, Jul 8, 13 at 14:02

Sizing a pump for Drip Irrigation - Can I use a 1.5 HP, 2" outlet to pump RO treated water to my plants?

I have two 330 gallon tanks, filling with RO treated water. Each has a 2" outlet. I want to set up an automatic drip irrigation system for 200 potted plants in 15-gallon containers.

The rise would be at least 2 feet. I figure that I would set leads from the tanks into a pump which could then push the water through drip irrigation tubing up to the plants. I am very cautious and afraid to get started. I assume each drip emitter will be 1-4gph, and I would like to water for less than an hour.

So, I have a used pool pump, 1.5 HP with 2" inlet/outlet. Can I just hook this up to the tanks and turn it on? Would downsizing the outlet to a 1" drip line cause the water pressure to blow out? I can water the plants in sections if necessary.

My alternate option would be to use a 0.5HP 1" pump.

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RE: Sizing a pump for Drip Irrigation - Can I use a 1.5 HP, 2" ou


Here is how I would look at this problem.

1. What is the water demand per day or week for your plants at maturity? My general estimate is about 1.0 gal per plant per week. If very arid climate say1.5 gal per week for 200 plants is 300 gal per week. That is equivalent to one of your tanks which is good storage capacity. Do you produce 300 gal per week in rainfall?

2. You need to find out the flow and pressure of your 1.5 HP pump. The outlet size does not matter at this point. The smaller the pipe size the more velocity in the pipe. Velocity is only harmful when it exceeds 5 fps and can cause water hammer(blowouts). You can look up a 1.5 hp pump that is similar to yours on Google and see what the pressure is. The pressure is important because you are using it directly for drip.

3. Size a pump that would put out 150 gals for 25 mins. That would be a 6-10 gpm pump with 10-15 psi operating pressure. I bet your pool pump would be a lot more than that. You probably would need a pressure reducer on you pool pump. and gate valve to restrict flow.

4. Let us know what you find out or have more questions.

5. Aloha

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