# How to fix uneven irrigation



## Ahab1997 (Jun 30, 2018)

So I've run into some highly stressed spots in my Bermuda.

I'm 99% sure it is due to uneven irrigation across the yard. I did a test last night and collected irrigation in two stressed/brown areas and one area that is nice and green. Based on the picture below, care to guess which jar was where?



So how do I go about addressing this? Is this a "DIY" thing, or should I call in a pro? The backyard is one big zone. Sprinkler heads are rotary nozzles, I think they're Rain Birds if I had to guess, but I haven't had a chance to check more closely.

Any advice would be most appreciated


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## g-man (Jun 15, 2017)

Not an easy dyi thing. You need to design the entire system correctly. This is a job for a real pro. Like one that will show you the design prior to building.


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## Ahab1997 (Jun 30, 2018)

Yeah, that's what I was figuring. Just to be clear, the system was professionally installed when the house was built (2.5 years ago), and verified, etc etc. I wasn't suggesting doing my own in-ground irrigation install. 

I imagine that even if the system was perfect at the start, some things have shifted over time, dirt may have crept into spaces, etc.


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## wafflesngravy (Apr 8, 2019)

g-man said:


> Not an easy dyi thing. You need to design the entire system correctly. This is a job for a real pro. Like one that will show you the design prior to building.


I gotta disagree with this statement, especially on a DIY forum. Every aspect of life is DIY, just depends on the person. OP can certainly do this himself and with the knowledge on this site OP could be very successful. Whats the point of this forum otherwise? Should the top banner read "Call a Pro, thanks for stopping by"?

If @Ahab1997 is serious start reading and asking questions. Posting pictures would help. It's hard to say where the issue is by your description. Could be as simple as a rotor not turning as far as it needs to, or as complicated as redoing the entire system. Both can be done by you if you so chose.


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## Ahab1997 (Jun 30, 2018)

Some of it seems pressure/flow related. I don't see any leaks in the system (no puddles in the yard, etc), but that doesn't mean there isn't one somewhere, or clogging somewhere else.

All the rotors still appear to rotate properly, but without the right flow behind them, you'll never get enough output.

If you want pictures of anything in particular, just let me know.

For the time being, I'm hand watering the stressed areas to try and alleviate the dryness. With temps regularly over 100F, it is a daily battle.


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## wafflesngravy (Apr 8, 2019)

An easy way to check for leaks is make sure no water is running anywhere in the house, then see if your water meter is moving. Did the grass used to look good but just recently started having problems? On my system the valves guts can get clogged and replacing them fixes low water pressure issues. They are easy to fix with a screw driver and a youtube video.


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## Ahab1997 (Jun 30, 2018)

The problems didn't become super obvious until it started getting really hot here (100+). I'll check the meter tonight.

I'm leaning towards clogging (or hoping, since that's an easier fix). At a minimum, pulling a head and checking the body shouldn't be too hard, right?


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## g-man (Jun 15, 2017)

For now, you can water a longer duration to get the low areas some water.

If you want to fix this, start by drawing the heads, distance between them, what heads are in each zone and head model and nozzle size.


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## Ahab1997 (Jun 30, 2018)

I'm just hand watering the stressed-out spots for now.

I can map the system, and I map already have a map from the original install that was done when the house was built, I'll have to go dig in the garage this evening.


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## hsvtoolfool (Jul 23, 2018)

DIY all the way. I agree that this should be correctable with a map, writing down the precipitation rates, and making adjustments. I've never installed rotors, but aren't replaceable nozzles with different GPM available? Don't you just loosen a screw, pop out the old nozzle, then pop in a new nozzle? Provided that the installer didn't mess up the head layout badly, you should be able to install lower GPM nozzles where you now have too much flow, and perhaps larger nozzles elsewhere to get better balance.


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## Ahab1997 (Jun 30, 2018)

So it looks like I'll need to make a map, and then get a bunch of catch cups to map out GPM across the lawn.

At least nozzle replacement with Hunter MP rotors looks very simple.

UPDATE: Checked the water meter this morning. Zero observed movement, so if there's a leak, it would be inside the valving of the system. Still not enough evidence that a leak is the cause of the issue.


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## hsvtoolfool (Jul 23, 2018)

From what you've described, I suspect that just swapping a few nozzles should do the trick.

When you have your map, the first layout issue to check is "head to head" coverage. Every head should spray onto (or a little over) all the neighboring heads. That layout design will tell us a lot about the competency of your installer.


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## Ahab1997 (Jun 30, 2018)

Yeah, it feels like the MP 1000 that is supposed to cover one of the dry spots just isn't doing its job. I hoping either adjusting it or swapping to an MP 3000 will fix it. I"ll probably give it a few turns with a screwdriver and see if that improved the situation.

If that doesn't work, then I'm definitely looking at a flow problem.


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## SwBermuda (Jun 9, 2019)

what is the sq footage of your yard @Ahab1997 ? How many mp rotors?


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## Ahab1997 (Jun 30, 2018)

23oo sqft or so. I'd have to go and count them (too dark at the moment), but at least 10 heads if I had to guess (but it could be more)

I plan to check the filters on some of the obviously weaker heads on Saturday morning before doing a full map.


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## hsvtoolfool (Jul 23, 2018)

Ahab1997 said:


> Yeah, it feels like the MP 1000 that is supposed to cover one of the dry spots just isn't doing its job.


My bad! I thought you had rotors like the Hunter I-20s. Full rotors have much larger flow demands than the MP Rotators quasi-spray heads. The flow demands for the MP Rotators is much easier to meet. So I doubt flow is a problem.

I strongly advise that you DO NOT leap from a MP 1000 to 3000 nozzle. Measure the distance between heads and pick the nozzle that's spec'd no more than about 50% farther. The reason for this is you can only dial down the MP Rotator nozzle distance about 50% before the spray pattern and flow rates get really wonky and unpredictable.

For example, suppose the distance between heads is 15 feet. I would install the MP 2000 nozzle at each head since these are spec'd at up to 20 feet. I'd then dial back both heads to spray about 17 to 18 feet. That's minimum dial-back for a good pattern with only about 2 to 3 feet of over-shoot. I like to have a little over-shoot with the MP Rotators to account for real-world conditions like wind and grass height.

Speaking of grass height, what is your HOC? And what is the spray head heights? Before I started mowing below 1" with my Swardman Electra, I had some dry spots caused by the nearby blades of grass interfering with my 4" spray heads. I learned that if the HOC is above 1.5", then you probably need to install 6" spray heads with the MP Rotators. They need plenty of room above the grass blades to be 100% effective. Each little "needle" of water is at a slightly different angle, and the lower jets can hit grass blades very easily.


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## Ahab1997 (Jun 30, 2018)

My HOC is 1-3/4". Can't go lower right now, due to really uneven ground and scalping in places. The struggle is real!

There's plenty of clearance between the spray heads and the top of the turf, at least I thought there was. I'll double-check that as well this weekend when I'm looking at everything else.


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## g-man (Jun 15, 2017)

I looked at the images from your journal. Your backyard is fairly rectangular. We will need a layout of the heads to further help.

Changing from mp1000 to mp3000 will also change the gpm for that zone. Your zone might not be able to handle it.


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## Ahab1997 (Jun 30, 2018)

I'm going to try and avoid nozzle swaps if at all possible. I'm hoping it is dirt/debris buildup in filters.


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## hsvtoolfool (Jul 23, 2018)

g-man said:


> Changing from mp1000 to mp3000 will also change the gpm for that zone.


I thought the MP Rotators were designed to have the approximate same 0.4-ish GPM across the entire family, with exceptions for the street strips and short-throw nozzles. So you can mix them without too much worry.


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## unclebucks06 (Apr 25, 2018)

hsvtoolfool said:


> g-man said:
> 
> 
> > Changing from mp1000 to mp3000 will also change the gpm for that zone.
> ...


The are matched precipitation but a larger radius requires more gpm.


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## g-man (Jun 15, 2017)

Most MP have the same precipitation rate of 0.4in/hr. When the design is correct, they will evenly apply 0.4in/hr to the entire area. But to do this, the nozzles with the larger radius has to flow more water (gpm) because the area is bigger.

The spec sheet list the gpm per nozzle and arc(90, 180, 360)


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## Delmarva Keith (May 12, 2018)

Ahab1997 said:


> So I've run into some highly stressed spots in my Bermuda.
> 
> I'm 99% sure it is due to uneven irrigation across the yard. I did a test last night and collected irrigation in two stressed/brown areas and one area that is nice and green. Based on the picture below, care to guess which jar was where?
> 
> ...


Read this: https://ww3.rainbird.com/documents/turf/IrrigationDesignManual.pdf

If you find it interesting and understandable, you are a good candidate to do it yourself. If it bores the heck out of you, pay someone else to figure it all out. The process goes along the lines of 1. what would the system be predicted to do if everything was working to spec; 2. Is it doing that and if not, what's broken, clogged, etc.; 3. Is what it's predicted to do adequate (proper original design); 4. If needed, change the design to get the desired result.

Your inclination to use catch cups as a diagnostic tool is a good sign that this may be your type of job. :thumbup:


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## Ahab1997 (Jun 30, 2018)

While I can't say I'll read all 129 pages, I think I have a good enough grasp of the design basics to at least assess the system and make some small changes to try and fix the problems.


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## hsvtoolfool (Jul 23, 2018)

unclebucks06 said:


> The are matched precipitation but a larger radius requires more gpm.


Of course! I was thinking about the wrong side of the nozzle. Duh.

Still, the flow rates of MP Rotators are relatively low. Unless the layout has marginal flow, I suspect you can swap out a few MP 1000 nozzles for 2000s without ill effects.

@Ahab1997, if you do find debris in a nozzle or screen, do a full flush on all the heads. It's a pain and you'll need some good chest waders, but flushing the pipes will help prevent a recurrence. The MP Rotators are sensitive to debris, and skipping a thorough flush during the install is too common.


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## Ahab1997 (Jun 30, 2018)

Chest waders? BAH! It's 105F here, I'll welcome some time playing in the sprinklers! ha ha


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## Biggylawns (Jul 8, 2019)

Did you swap the rainbirds to MPs yet? What is your gpm #? Your yard, based on your journal, looks fairly easy to map out but sprinkler pic locations would be very helpful.


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## Ahab1997 (Jun 30, 2018)

They're all MP rotators. I have a rudimentary map, just need the time to put it to scale, so I can get a good idea of coverage.


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## Ahab1997 (Jun 30, 2018)

OK, quick update while I decide to procrastinate at work for a bit.

Replacing two of the spray heads with slightly longer reach heads appears to be helping with one spot.

I both catch cups and did a survey of the yard. There is one part (just a few square feet, but it is obvious) that is getting essentially no irrigation. I don't know why the design left such a gap. I'm considering adding a head that would service that area, but that's a project for MUCH cooler weather.

This area also was a gap when I did a map of the heads and their spray radius, so it wasn't too surprising to see it.


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## g-man (Jun 15, 2017)

Where is the map?


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