Doesn't sound quite right to me. The more zones you break it into the lower the gpm needed and the smaller pump. I would look at only single phase. Some questions can help with to check your calcs.

1. What flow rates and what pressure are the Hunter heads designed(specified) for?
2. What is the vertical distance(ft) from the bottom of the tank to the top of the heads?
3. Is your info from a pump curve for a specific pump?
4. Most Big Box stores or irrigation stores sell submersibles. You have the right idea there. JMHO Aloha

Three phase would be cheaper to operate and the pumps are usually cheaper. On the other hand, between your utility's charge to get you the service plus getting your wiring done, it might cost you an arm and a leg to get the service. Wouldn't hurt to ask the utility what they'll do and for how much.

Personally, I prefer 3-phase submersibles, but, I'm running municipal well pumps.

Michael,

What is your call on a 60 gpm and 65 psi submersible pump? Aloha

Lehua13, please be more application specific, static head, etc., I assume you aren't pumping raw sewage with it :) BTW, I am not an engineer, just a mostly self educated city employee keeping the taps flowing.

1. What flow rates and what pressure are the Hunter heads designed(specified) for? The heads vary in gpm and pressure, but I would set them up so each was at 10gpm, thats 60gpm@ 50 psi. The heads can run as low as 30 psi

2. What is the vertical distance(ft) from the bottom of the tank to the top of the heads? 8 ft

3. Is your info from a pump curve for a specific pump? Calulation.

4. Most Big Box stores or irrigation stores sell submersibles. You have the right idea there. I am not confident the standard 1/2 or 3/4 HP pump will fit the bill here. But that's the question I am trying to answer.

Wianno,

By calculation HP is: QHS/e3956; Q=flow in gpm; H=head in feet;S=1 for water; e=efficiency(80%); 3956=conversion unit factor to end up with HP so 50 psi/0.4333psi/ft= 115 ft; total H=115ft+8ft.

60gpm x 123 ft x 1 /(0.80)x 3956 =2.33 HP Say 2.5 HP

30 gpm x 123 x 1 / (0.8) x 3956 = 1.17 HP Say 1.5 HP if you split the heads into two zones. Price out the difference in pumps.

Look at more smaller heads in more zones versus fewer large heads using a much bigger pump. aloha

That will be $0.02 please. Aloha

The system is already set up, so trying to dig up and split my zones would be alot of work, but might be worth it once I start looking at pump cost.

Do you have any suggestions on web sites to look at pumps this size? I am specifcally looking for submersible.

wianno,

No, I use just google. maybe find a consumer rating article on pumps. Go with a reputable company that backs it product locally. Just curious what is the area you are irrigating? You are using large output irrigation head nozzles. What if you lowered your output nozzles and ran for a longer time. How may gallons would you use per cycle of irrigation? Aloha

Wow, you know something, your right! I looked at the PGP chart again and realized I am a factor of 10 off! Instead of 10GPM/head, I meant 1GPM/head. But my system is currently set up to run at about 2-3GPM/head. Using your calc above, I could easily use a 1.5HP pump, not the 3Hp I originaly calculated. I could also run the system at 30-40PSI with little impact to head performance, so I should do the calc at 40PSI, not 50PSI.

Using your formula:
40 psi/0.4333psi/ft= 92 ft: H=92ft+8ft =100ft
(3gpm x 6 heads)x 100 x 1 / (0.8) x 3956 = .56 HP. Looks like I might be able to get a 3/4 hp pump to fit the bill easily.

Here is a link that might be useful: PGP head flow

Wianno,

I would go with a little extra umph and flow. I don't believe a 1 hp is that much more money than a 3/4h hp but it may be several hundred dollars in the high quality range. Also look at how long it will take to empty the tank and what you will do to fill it up again. Is this a gray water system or rainwater or both? We can calculate your water need and therefore your watering time by knowing your area(sf). Aloha

1000 gallon tank fed by about 1500 sqft of roof and some runoff. I am adding an addition and thinking of diverting the shower and sink to the tank too, but runoff could be a problem in this case. Not sure I am up to this yet, but I may plumb it to have the option.

I figure its only good for the front zones of my property, about 2000sqft of lawn. Total lawn is about 5000sqft.

W,

Average about 1" of water on your lawn a week. 2,000 sf x 0.083 ft = 166.7 cf x 7.481 gal/cf = 1,247 gal/week needed. If you have drought tolerant grass variety, cooler temp less, water hog grass variety, hot temp more. How much will your gray water/rainwater system produce a week? What is your monthly rainfall pattern for your area? You could set up your system to go cistern pump with City water backup. JMHO Aloha