# 4" or 6" popup



## kolbasz (Jun 7, 2017)

If I mow at 3.5 or 4, should I have 4" or 6" pop-ups?

At 3.5 with 4" ers, I seem to get interference from the grass. Am I doing something wrong or should I just use 6" pop-ups instead?


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## Ecks from Tex (Apr 26, 2018)

If the ground is completely flat, 4 inch is fine. If even the slightest slope, I move up to six inch. You are technically supposed to keep the grass away from the pop ups though....I just get better coverage with a 6


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## g-man (Jun 15, 2017)

If you mow at 4in, you likely let it grow to 6in before mowing, therefore you want 6in pop ups to avoid the spray hitting the blades.


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## hsvtoolfool (Jul 23, 2018)

At 3" HOC or above, I'd definitely use 6" pop-up heads. Better safe than sorry.

I know the Hunter MP-Rotators need lots of extra space above the grass to achieve even watering. For these, I'd use 4" heads only at 2" HOC and below. The reason is that each head shoots many tiny streams, with each stream at a different angle. The tiny streams are fragile and can be deflected by any grass blades growing near the head. The result was a few dry spots. After dropping from 3" HOC to 3/4" HOC, I noticed a significant improvement in my coverage with my 4" pop-ups.


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## kolbasz (Jun 7, 2017)

Yeah, Im thinking 6 is the way to go. The maxi paws can power through the grass, but not the fine spray on the 4"er


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## lawn789 (Jun 16, 2019)

If I had it to do over again Id try and do 6" pop ups.


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## kolbasz (Jun 7, 2017)

Here is one, hunter or the rb 1800's


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## hsvtoolfool (Jul 23, 2018)

I'm a Hunter fan. And an MP-Rotator fan. And a Sprinkler Warehouse fan. I hope soon to be a RainMaker smart controller fan. That's next on my "to do" list. I have a Hunter Pro-C controller, and it's okay for what it is I guess.... but I'm not a fan of that thing. It's going buh-bye soon.


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## kolbasz (Jun 7, 2017)

hsvtoolfool said:


> I'm a Hunter fan. And an MP-Rotator fan. And a Sprinkler Warehouse fan. I hope soon to be a RainMaker smart controller fan. That's next on my "to do" list. I have a Hunter Pro-C controller, and it's okay for what it is I guess.... but I'm not a fan of that thing. It's going buh-bye soon.


Are the mp's good if I only need to Go 10' spray?


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## hsvtoolfool (Jul 23, 2018)

The MP-1000 are rated 8 to 15 feet, so I'd let those run at the max range of 15' for your 10' head-to-head coverage. You might dial them back to about 12 feet if conditions are perfect: no wind, no slope, no tilt to the pop-up head.

If needed, it's also very easy to swap out to MP-2000 nozzles later and then dial back the distance. These nozzles just screw onto the top of the pop-up. You don't need to dig up the spray head or anything. It literally takes about 30 seconds to swap a nozzle out.

Don't expect perfection out of the gate with any brand you use. You'll probably need to swap in a bigger nozzle here or there after the final install. Elevations, spray head angles, and prevailing wind means you must tweak things later. Most of your time is spent adjusting the aim and range of the nozzles. If you don't have any chest waders, then I advise you get some! With any spray head system you'll get soaked while adjusting their range and aim.

Head-to-head coverage with a little overlap is key for any spray head, but especially for the MP-Rotators. Irrigation parts are cheap compared to the time and labor it takes to install them. So don't "cheat" and try to go with fewer heads that spray halfway. That's not how these heads were designed. In theory, each spray should hit right at the next head. But in my experience, the MP-Rotators work best when they overlap by a couple feet.

And if you're using any of the specialty side-strip nozzles, then overlap by at least 30% to 50% past the next head. I'm talking lots of overlap! All side-strip heads from every maker are inefficient. It's really hard to make a head that sprays an oddball 15 x 3 foot area.

One big issue with the MP-Rotators is pressure. They want exactly 40 PSI and no more. Most problems I've read on the web come from folks sending way too much pressure to the nozzles, which then causes fine misting and eventually damages the gears inside the nozzle. I installed a Pressure Reducing Valve (measured at exactly 50 PSI!) and installed the Hunter "Pro-Spray" heads. These have 40 PSI regulators and check-valves inside each spray head. They were practically the same price as the heads without these extras. I bought the heads and nozzles separately in bulk, but they now offer the spray heads and nozzles bundled together.

Finally, I don't have any experience with the Rainbird spray heads or their version of MP-Rotators. I'm sure they're okay too. I just wouldn't make my decisions based on what's available at the local big-box store. Someone in another thread was doing that and I just didn't understand the logic. It's so convenient just to order the pro-level gear from an online retailer with a solid reputation. In an emergency, I promise you there's a local irrigation store that sells the pro-level gear at triple the online price. No joke, I thought my local Site-One store was insane when they told me their price for MP-Rotator nozzles. I bought my nozzles on line for a fraction of their price. I keep extra heads and nozzles around for when something gets broken (knock on wood).


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## kolbasz (Jun 7, 2017)

hsvtoolfool said:


> The MP-1000 are rated 8 to 15 feet, so I'd let those run at the max range of 15' for your 10' head-to-head coverage. You might dial them back to about 12 feet if conditions are perfect: no wind, no slope, no tilt to the pop-up head.
> 
> If needed, it's also very easy to swap out to MP-2000 nozzles later and then dial back the distance. These nozzles just screw onto the top of the pop-up. You don't need to dig up the spray head or anything. It literally takes about 30 seconds to swap a nozzle out.
> 
> ...


Thanks. Yeah, bought one head at site one, never again. It was and mp pro I think. One of the bigger ones as a manual sprinkler.

My setup is for the strip between the sidewalk and street. There are currently 7 heads, taking this to 11. I know I should technically be at the street and the sidewalk, but I dont need people driving on the heads, plus the plows, so I am just upping the overall output.

I like the rainbird rvan heads just because they allegedly do not get clogged like the MPs which need to be replaced at like $6 a pop every time. Plus, I believe I do not need to regulate the pressure the same way. 30-55 with a recommendation of 45PSI.

The pressure regulated heads are double the price. Unless you think that is absolutely needed, its $100 extra.


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## hsvtoolfool (Jul 23, 2018)

kolbasz said:


> I like the rainbird rvan heads just because they allegedly do not get clogged like the MPs...


Whatever works. I suspect they're all about the same and have the same issues. When it comes to clogging, I think it's all about how clean the water supply is, installing filters, and repeat, meticulous flushing during the install. I've had zero problems with my system so far, but it's only been 3 years.

If we open our books to the "Gospel of Stryker", then a 60 mesh filter should be installed before any backflow preventer, while a 100 to 120 mesh filter should also be installed before geared spray-rotor nozzle type systems. Amen.



kolbasz said:


> Plus, I believe I do not need to regulate the pressure the same way. 30-55 with a recommendation of 45PSI.


I would plan on regulating the pressure anyway. Measure your static pressure at the street. If it's more than 60 PSI, then install a Pressure Reducing Valve dialed down to about 50 PSI. My static pressure at the street was shockingly high. Without that PRV installed, the pressures would destroy any geared-spray head eventually. It's really hard to avoid water hammer issues at 90 PSI and higher.

It's not surprising the specs you listed for the RainBirds are practically identical to the Hunter MP-Rotators. Less than 30 PSI and maybe the heads won't pop up. More likely, you won't get the needed distance and GPM rates. Not much you can do about that except talk to the water utility. Pressures much over 50 PSI can cause misting. Rainbows are pretty and everything, but mist is just water blown away and wasted. And of course really extreme over-pressures (and water hammer from poor design) physically damages the mechanisms in any geared spray nozzle regardless of manufacturer.



kolbasz said:


> The pressure regulated heads are double the price.


We'll just agree to disagree on that one. For me, that's one of those "Missing the forest for the trees" arguments. Believe me, the money spent on irrigation parts is trivial compared to the time and labor required to install an entire irrigation system. For that reason alone, I want the very best parts installed once and done.


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## kolbasz (Jun 7, 2017)

@hsvtoolfool you are probably right. I was thinking the PSi from the city is below 45, but it seems normal is 40-80.

In that case, it seems worth it to get the pressure regulated ones, so there is constant pressure. The only real question is what happens below 45PSI, I assume they do not pop up?

If the PSI is 50 and I have a bunch of heads, is there a way to calculate how many PSI each head bleeds from the overall.

I have 7 normal spray type heads now and it has always been fine. The last thing I want to do is go to 11 heads with a static PSI and suddenly they do not pop up. My thought was to get one of those 10$ pressure gauges and check the PSI to know what I am working with.


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## hsvtoolfool (Jul 23, 2018)

kolbasz said:


> The only real question is what happens below 45PSI, I assume they do not pop up?


Given the specs you provided, I'd say 30 PSI or below is where pop-up issues will begin occurring. I'm sure 40 to 45 PSI will be fine for either Rainbird or Hunter geared spray nozzles.



kolbasz said:


> My thought was to get one of those 10$ pressure gauges and check the PSI to know what I am working with.


Yes! Highly recommended! It's always worthwhile (and easy!) to check the "Static" pressure with a gauge. I strongly recommend installing a PRV for any street pressure above 60 PSI. Even if each spray head is regulated exactly at 40 PSI, pressure is a big factor for water hammer. You can destroy pipes, valves, heads, or nozzles with excess water hammer. While we can't escape some water hammer, the system can be designed to keep the water hammer at safe levels. Limit pressures, size the pipes correctly, and limit zone head counts.

Neither Rainbird nor Hunter sell crap gear, at least not in their "pro" lines. I suspect that most horror stories you hear about with failures is caused by poor system design. Too low GPM / pressure and the system won't break, but it won't work right either. Obviously, too high pressure and flow causes excessive water hammer which destroys the weakest items in the system first, and the stronger items later.

*Anyone planning DIY irrigation install should read and understand the entire Jess Stryker web site.* It's free content, he really knows his stuff, he explains it well, and the original content is still available at the Internet Archive. I cannot recommend his web site highly enough. I am not a professional irrigation installer. But thanks to Mr Stryker, I know 1000 times more about irrigation design than 99% of the local-yahoo-rip-off-artists who call themselves "pros".



kolbasz said:


> In that case, it seems worth it to get the pressure regulated ones, so there is constant pressure.


I set my PRV Static pressure at 50 PSI, so I'm slightly "over pressure" for all heads in my system. I rely on the regulated heads to provide the ideal 40 PSI to each spray nozzle.

Alternatively, I could have used un-regulated heads and instead added a 40 PSI pressure regulator to each Hunter globe valve so each zone would be correct.

The head check-valve feature is also very nice since the pipes stay full and there's no delay when the system comes on (also no hissing, sputtering, etc. from air in the pipes).



kolbasz said:


> If the PSI is 50 and I have a bunch of heads, is there a way to calculate how many PSI each head bleeds from the overall.


Pressure for a steady-state system is constant. So all heads on a zone will be about the same PSI. The two possible states for an irrigation system are off (closed) and running (open). So a "Static" pressure exists when the system is off while a second "Dynamic" pressure exists when a zone is running.

Think of your irrigation system as an inflated balloon. The pressure is identical everywhere inside the balloon. This is the "Static" pressure. We now poke a hole so that the balloon slowly leaks. The pressure is now "Dynamic" and gradually drops until it reaches zero. However, let's now suppose that the balloon is _re-filled faster than it's leaking_. If the re-fill rate barely keeps the balloon inflated, then the "Dynamic" pressure is significantly lower than the "Static" pressure. If the re-fill rate keeps the balloon fully inflated, then the "Dynamic" pressure will be the same as the Static pressure. This is a theoretical ideal. In reality, the Dynamic pressure is always lower than the Static pressure.

When a zone valves opens, the pressure drops to a new "Dynamic" pressure value and stabilizes. But this pressure is still the same everywhere in the system, just at a lower value than the "Static" pressure. The Dynamic pressure value _for each zone_ is ultimately determined by the operating GPM / pressure for the zone's heads relative to the water supply GPM / pressure.

If the water supply lacks the GPM / pressure to keep the balloon inflated, then use fewer head and more zones. If your water supply is crazy-high GPM and pressure, then in theory you could run all the heads for your entire lawn on one zone. In reality, you must reduce the total heads per zone to keep the water hammer to safe levels.


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## g-man (Jun 15, 2017)

^+100

www.irrigationtutorials.com is the Jess Stryker (or sprinkler warehouse now) site to follow. His design steps are spot on and will save you headaches in the future.


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## kolbasz (Jun 7, 2017)

Of course I go get a pressure guage and some pvc, but I only to come home and find my pvc cement dried up


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## kolbasz (Jun 7, 2017)

@hsvtoolfool

OK, I this is what I am working with.



If I open the faucet next to this I drop to 40



If I turn the system on I drop to 40



Obviously when in line I will drop, but want to confirm still. Will the 45psi regulated heads be good if I am seeing 60psi with things off?

Also, this dumb thing leaks, even with plumbers tape. Any suggestions to make it stop. It is a slow drip, but a drip regardless


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## hsvtoolfool (Jul 23, 2018)

kolbasz said:


> Will the 45psi regulated heads be good if I am seeing 60psi with things off?


You'll be fine.


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## kolbasz (Jun 7, 2017)

hsvtoolfool said:


> kolbasz said:
> 
> 
> > Will the 45psi regulated heads be good if I am seeing 60psi with things off?
> ...


By fine do you mean with the 45 PSI heads1 or with either one


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## hsvtoolfool (Jul 23, 2018)

The static pressure is about 70 PSI, the dynamic pressure _at the hose bib_ is about 40 PSi. I'd bet the dynamic pressure at the heads will be close to 60 PSI. It's your choice to install a PRV and/or regulated heads to avoid water hammer and lower risk of damage to components. My earlier post discusses this topic. Really, I just wanted to steer you to Mr Stryker's great write up. If you're in a rush, just do what most folks do; slap it together with no calculations and fix any problems that occur after the fact.

By the way, I never measured my dynamic pressures. I followed the steps outlined by Mr Stryker. His method uses max street flow (GPM), static pressure, and simple math sums for each head's rated flow (GPM) to define how many heads can exist per zone. My guess is that without pressure regulation you will either get misting or water hammer. I hope this helps. @g-man can chime in if I've misunderstood what you're doing.


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## g-man (Jun 15, 2017)

I'm kinda lost in this thread. The original question was around 4 or 6in. Now the question is whether to use regulated bodies or not? My default answer is regulated bodies with CV.

If you still have the gauge, check it as 6am when most irrigations are running. My pressure is very different at 6am.


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## 7474 (Aug 20, 2018)

lawn789 said:


> If I had it to do over again Id try and do 6" pop ups.


2nd this


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## kolbasz (Jun 7, 2017)

g-man said:


> I'm kinda lost in this thread. The original question was around 4 or 6in. Now the question is whether to use regulated bodies or not? My default answer is regulated bodies with CV.
> 
> If you still have the gauge, check it as 6am when most irrigations are running. My pressure is very different at 6am.


Yeah, we got to hear discussing head size and then it turned into some general topic discussion.

Goal is to do the upgrade once, the right way and be done.


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## CenlaLowell (Apr 21, 2017)

I mow at 4 inches so I'm definitely going with 6 inch pop ups. Okay looking at this prices 6 inches are much more expensive.


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## kolbasz (Jun 7, 2017)

CenlaLowell said:


> I mow at 4 inches so I'm definitely going with 6 inch pop ups. Okay looking at this prices 6 inches are much more expensive.


So much more, I ended up going with 4's


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## CenlaLowell (Apr 21, 2017)

kolbasz said:


> CenlaLowell said:
> 
> 
> > I mow at 4 inches so I'm definitely going with 6 inch pop ups. Okay looking at this prices 6 inches are much more expensive.
> ...


If I end up going with 4 inch pop ups I'll lower my cut to 3 inches


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## dleonard11122 (Jun 24, 2020)

FWIW I mow at 4" in the summer and don't have any issues with my 4" Hunter PGP Ultras. Maybe I don't have the heads installed flush with the ground and they're a little bit proud. Either way, with rotors I don't notice an issue with grass deflecting the stream.


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## hsvtoolfool (Jul 23, 2018)

I agree that a rotor stream won't be deflected by tall grass (within reason). Sprays and MP Rotator have multiple, thin, fragile streams shooting at several angles. I noticed that my MP Rotators work best when they're well clear of the average HOC.

If your final HOC is 3", then you'll probably mow when the grass reaches about 4" to 4.5" tall. That's even with the top of the spray heads and you'll likely get some deflection at that height. But you can time your watering schedule to get proper irrigation coverage. Mow a day or two before your weekly irrigation when the grass is shortest.


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## TSGarp007 (May 22, 2018)

I had 4" rotors and SA grass mowed at 3.5-4". It most definitely affected my rotor pattern. Almost all of mine are now 6" whether rotor or rotary stream like R-VAN or MP Rotator. Is there any reason not to sue a 6" body instead of a 4"?


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## dleonard11122 (Jun 24, 2020)

TSGarp007 said:


> Is there any reason not to sue a 6" body instead of a 4"?


1. They're more expensive. 
2. They aren't as common, so more difficult to source. 
3. You need to dig deeper to fit them.

That's about all of the reasons I can think of. Reasons 1 and 2 are probably the deal breakers for me. I'm particular to the Hunter PGP Ultra's, and they only come in 4" and 12" popups.


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## TSGarp007 (May 22, 2018)

dleonard11122 said:


> TSGarp007 said:
> 
> 
> > Is there any reason not to sue a 6" body instead of a 4"?
> ...


That's true. Although it shouldn't be in my opinion. With a majority of saint augustine grass around my area, 6" should be the norm at the big box stores, though it definitely isn't. That is annoying about the Hunter line, you have to go I-20 to get 6".


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## dleonard11122 (Jun 24, 2020)

Yeah, if they were more readily available I wouldn't hesitate to install 6's, but the 4's are really the standard around me so it's what I go with.


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## CenlaLowell (Apr 21, 2017)

dleonard11122 said:


> Yeah, if they were more readily available I wouldn't hesitate to install 6's, but the 4's are really the standard around me so it's what I go with.


That's what I'm seeing as well. In some cases 6 inch is almost double the price of the four inch crazy.


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