# Switching from Hunter PGP's to MP Rotators for the Lawn



## GHTech (Mar 15, 2021)

Greetings,

I currently have 6 Hunter PGP's (in 2 zones) for my 2,000 sq. ft. Bermuda lawn for the last few years. Seems to be having coverage issues (pictures below). I have Hunter MP Rotators in my plant beds. Considering switching over the lawn to MP Rotators. My current setup has 3 PGP's 28 ft. apart on each side. Side to side distance is 31 ft. If I go with MP Rotators, should I get MP3000 (22' to 30' radius) or MP3500 (31' to 35' radius)?

Thanks,

GHTech


----------



## raymond (May 4, 2018)

I'd think you'd water the mp3000.... you want h2h or less (even 80% coverage is good)

I just installed my whole system with the mp2000s and 3000s.. love them


----------



## g-man (Jun 15, 2017)

You will need to draw this up just to see the current head locations. Is it a total of 3 heads?


----------



## Utk03analyst (Jun 8, 2019)

I would be very interested in the differences you see. I've heard such good things about the rotators but my side yard is 45x 100 and I put in pgp's. I have a smaller area with pgj's I've been considering rotators and built a play gym out back which now gets soaked by my pgp's.

Just wondering if the juice is worth the squeeze.


----------



## GHTech (Mar 15, 2021)

g-man said:


> You will need to draw this up just to see the current head locations. Is it a total of 3 heads?


HI,

My lawn is rectangular. I have 3 PGP's along each side (longer sides).

Regards,

GHTech


----------



## bernstem (Jan 16, 2018)

Once you have the spray bodies in, changing from 3000 to 3500 is just the nozzle. They are about 5-6 dollar each so if you don't get coverage it doesn't cost much to up or down size unless you have dozens of heads.


----------



## g-man (Jun 15, 2017)

I dont think switching to MP is going to be a difference in this scenario. The PGP should be able to water this area without a problem.

Are the current heads distance spraying each other? Meaning the stream of one head hits at least two heads (one across and one norht/south)?

If so, then how long are you running the irrigation? You want to irrigate at least 0.5in using a straight wall container (eg. empty tuna can) every 2-3 days (most likely 2 right now in your area).

Make sure the corner heads use a nozzle that is half the size than the 180 heads.


----------



## spaceman_spiff (Feb 5, 2021)

g-man said:


> Make sure the corner heads use a nozzle that is half the size than the 180 heads.


Can you elaborate on this? I just use the same nozzle on my corners as my 180s and just reduce the arc. I think you're alluding to over-watering if you have the full radius on the corners?


----------



## g-man (Jun 15, 2017)

Check the hunter design guide in their website.

The ratio should be 4:2:1 for 360, 180, 90 heads. A 360 has to do a full turn, vs a 90 is only a 1/4 of a turn. To get even distribution of water, the 360 will need to deliver 4 times the gpm than a 90 degree.


----------



## Utk03analyst (Jun 8, 2019)

g-man said:


> Check the hunter design guide in their website.
> 
> The ratio should be 4:2:1 for 360, 180, 90 heads. A 360 has to do a full turn, vs a 90 is only a 1/4 of a turn. To get even distribution of water, the 360 will need to deliver 4 times the gpm than a 90 degree.


What g-man said unless your arcs are on different zones then you can use the same ratio on your run times to put down the same amount of water. When I designed and did my install I put my 180's and my 90's on different zones but It doesn't have to be that way. Major reason was because of distance the higher gpm nozzles normally give more distance which I needed for head to head coverage.


----------



## g-man (Jun 15, 2017)

Yes you can do that too. Mainly with the 360 in a separate zone, but it is rare and hard to program with a rachio. It is still getting you the same ratio just by changing duration instead of GPM nozzle.


----------



## GHTech (Mar 15, 2021)

Greetings,

I picked up 6 of the Hunter MP3500's and 6 PRS40 (pressure regulated)bodies couple of days ago. While swapping the bodies (replacing the Hunter PGP's), found that there was no moisture in the clay soil that I dug up. It was bone dry, and the Bermuda roots were about 1" deep. I am not sure what was going on with the PGP's that I had. I had the 2 180 degree ones with the 3.0 nozzle, and the 4 90 degree ones with the 1.5 nozzles. They ran for about 30 - 40 minutes on 2 or 3 times a week on the Hunter Pro-C with the Solar Sync.

Anyway, after installing the MP Rotators and new bodies, and ran the system for 30 minutes, and was getting around 0.25" of water all over the lawn. After a little bit more adjustment am getting 0.25 throughout. I did check the pressure at the Spigot that is on the irrigation line, and was getting 60 PSI. I tried to run both MP Rotators zones (3 MP3500 each) together, but the streams was not performing as good as when I ran the zones separately.

I was told that I should put down about 1.5" per day for the next week. I am working on that.

Regards,

GHTech


----------



## raymond (May 4, 2018)

Nice!


----------



## bernstem (Jan 16, 2018)

Great! You shouldn't need 1.5 inches/day if that is what you meant. I would give the lawn 1.5 inches to replenish the soil and then move to regular watering. As long as you don't let it dry out, the water will percolate down the soil profile. If you give it 1.5 inches per day, you will have a swamp.


----------



## GHTech (Mar 15, 2021)

bernstem said:


> Great! You shouldn't need 1.5 inches/day if that is what you meant. I would give the lawn 1.5 inches to replenish the soil and then move to regular watering. As long as you don't let it dry out, the water will percolate down the soil profile. If you give it 1.5 inches per day, you will have a swamp.


Hi bernstem,

I believe that what was suggested was to water it at 1.5" per day for a week, to build the water level down to about 8", and then switch to a more regular schedule. I already did the first 1.5" of watering early this morning. How much and when would you recommend the next watering to be? And the recommended frequency?

Thanks,

GHTech


----------



## bernstem (Jan 16, 2018)

GHTech said:


> bernstem said:
> 
> 
> > Great! You shouldn't need 1.5 inches/day if that is what you meant. I would give the lawn 1.5 inches to replenish the soil and then move to regular watering. As long as you don't let it dry out, the water will percolate down the soil profile. If you give it 1.5 inches per day, you will have a swamp.
> ...


How much to water to fill 8 inches of the soil water reserve will depend on soil type. For sand, it might be 1 inch of water. For clay it might be 3 inches of water. 1.5 inches per day for a week is almost a foot of water. I would be surprised if your soil will hold that much in the root zone. Most likely 1.5 inches has fully repleted the root zone of your soil and anything more added will move deeper than the grass can access.

If you want to make sure you have enough water, then water another 1.5 inches in a few days. After that water based on losses. That will vary from 1-1.5 inches per week for most temperatures. If it is 95+, it might be 2 inches per week.

You can tell when the grass needs water just by looking at it. The grass blades will get thinner and darker and the grass won't spring back from footsteps as fast. When you see those signs, you should give the grass water (probably ~1 inch). Ideally, you would water just before visible signs of drought stress, but that can be hard to do. With time and experience, though, you will be able to judge pretty well.


----------



## GHTech (Mar 15, 2021)

Greetings,

Wanted to update the thread with some newer pictures. After the MP Rotators were installed 8 days ago, I gave it a 1.5" dose the next morning. Since then, I have been watering every 2 days for for a total of 81 minutes. That is 30 minutes each (3 a.m., 4 a.m. and 5 a.m.) seasonally adjusted by my Hunter Pro-C with the Solar Sync. So, I am putting down about 0.6" every 2 days. We are having a few days just over 100, and there after just below 100. Always assumed that my soil is clay soil. But, I now believe that it is sandy loam.

Regards,

GHTech


----------



## bernstem (Jan 16, 2018)

Looking better. I'm not a Bermuda guy, but they all seem to encourage Nitrogen in summer to stimulate spreading. Give it some food and it should spread to fill in the dead spots.


----------

