Mesh size for lake intake screen

Discussion in 'Irrigation / Sprinkler Forum' started by birchlake, May 26, 2018.

  1. birchlake

    birchlake Member

    Jan 19, 2012
    Melrose, MN
    Hi All,

    I have a new residential sprinkler system, using lake water and powered by a Myers 2 stage pump. System is designed very well and is efficient.

    I have about 25 Hunter I-20 rotor heads and these are working perfectly and have no issue with lake water.

    The issue I am having is the smaller sprinkler heads as those have a filter as part of the head and the filters are getting clogged frequently. The heads in question are the Hunter MP-Rotator heads and also Rainbird VAN nozzle heads. It is mostly very tiny pieces of lake weeds that are making it through my lake intake screen and clogging the head filters. I have some very small areas of lawn that need irrigation and that is why my installer had to use some of these smaller heads instead of the I-20s in those tight quarters.

    I already have tried two things. My installer brought me a different intake screen with the smallest slots that he could find, smaller than the slots on the original intake screen. That didn't help. I then bought a KLEEN-FLO filter screen which I wrapped around my intake screen. The Kleen-Flo screen was smaller than the slots on my PVC intake screen and did help a little bit, but the head filters still clog frequently. I took the two head filters that are clogging down to the lake and placed them on top the Kleen-Flo screen for comparison. The Kleen-Flo definitely has square holes that are quite a bit larger than the mesh on the sprinkler filters so I can understand how the small lake material is making it through the line and up into the sprinkler head filters.

    To solve this, I believe that I need to have smaller mesh on the intake pipe than the mesh on the head filters.

    I found online a company named RUSCO offers three different what they call "basket strainers" (AKA intake screens) designed for irrigation systems. They offer a 24 mesh, a 60 mesh and a 100 mesh. The 24 mesh I don't believe would be enough so I think that one is out.

    The 100 mesh strainer filters down to 152 microns which is .0059 inches. I am leaning towards going with the 100 mesh but I'm wondering if 100 mesh might be too small and the strainer may clog quickly, impeding flow.

    The 60 mesh may be enough though too, and is still under consideration. The mesh size on the sprinkler head filters are in the 35-40 mesh range according to Hunter/Rainbird documentation. So if I filter at 60 mesh at the lake screen, maybe that will be enough prevent clogging of the 35-40 mesh head filters? I have a request into Rusco engineering for their recommendation but haven't yet heard back from them.

    My thought is that I could easily step into the lake and brush off the basket strainer weekly or as needed, which is one heck of a lot easier than cleaning the filters on 14 sprinkler heads and then having to make slight adjustments to some of them after doing so!

    Any recommendations on mesh size, if I go with a Rusco unit? Or any other ideas? I thought tonight about pulling the filters out on a couple of the Rainbird VAN Nozzle heads as an experiment to see if the nozzle heads would get clogged without the filters, but I don't have much confidence of that working long term as I think the nozzle heads will eventually clog.

    Thanks for any ideas!
    Last edited: May 27, 2018
  2. WorthFlorida

    WorthFlorida The wife is still training me.

    Oct 28, 2009
    Orlando, Florida
    There must be a lot of dead matter in your lake (probably normal) and any screen size will always get plugged up. The smaller the screen at the lake, more cleaning it will need but I would go with the 100 anyway. For now, get a nylon stocking and place it over the existing intake and see how it goes. Another is, if possible, move the intake further from the shore of the lake into cleaner deeper water. Supporting the extra pipe could be a challenge. Here in Florida a lot of lake water is used for irrigation and when you extend a PVC pipe into the lake, using a tee fitting you build legs with PVC pipe. The "legs" are capped off. Below is a rough sketch.

    It's no problem removing the small filter screens in the pop ups heads but eventually the small nozzles mayplug up but it depends on the size of the debris. I've had them plugged up without filters and it is sometimes a bear to clean them or not possible. By removing the filter screen also removes and adjustment to adjust the output or distance you want the popup head to cover. The small screw slot turns a phillips head screw that will raise or lower the head into the filter thus restricting flow. RUSCO has spin down filters but it can get expensive then you have winter freezing to content with. Regardless, an irrigation system is not maintenance free and the heads plugging up should be maybe once a year especially with MN winter, the irrigation system is only used a few months. I'm on city water and had another home on a well. It was usually old glue or bits of PVC that would plug up the filters but generally not fully and sometimes it affect the outflow and other times it made no difference.

    Last edited: May 28, 2018
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  4. Reach4

    Reach4 Well-Known Member

    Sep 25, 2013
    Consider putting a filter after the pump and readily accessible. If pressures are low enough a Twist II Clean filter might do the job. That is easily backflushed.
  5. birchlake

    birchlake Member

    Jan 19, 2012
    Melrose, MN
    WorthFlorida and Reach4, than you very much for your replies!

    I am building a stand for the intake pipe right now to keep it up and out into the lake further, and if I don't have any luck with filtering the lake water at the source, I will consider filtering after the pump.

    This morning, I spoke with Tech Support for both Rainbird and Hunter.

    The Rainbird rep didn't have much to offer except to refer me to their one inch in-line filter basket which has a 200 mesh screen. But we both agreed that 200 would likely be too tight and would clog quickly.

    The Hunter Tech Support guy supported my idea of trying the Rusco 100 mesh basket strainer and thought that 100 mesh is a reasonable size to try for my application with sediment in lake water, so I ordered one this morning. He said to be sure that the pump would be able to handle this filtration level though, so I checked the specs and the Myers pump puts out 29 GPM max and the Rusco strainer is specd for 100 GPM, so as long as I clean the Rusco strainer periodically, I think I will be okay.

    Another thing that I looked at is buying "bulk polyester mesh" (found a couple of sources, one being Component Supply Companies) that will sell small quantities. They offer mesh sizes ranging from 18 to 950. I could buy a linear yard of any mesh size I want pretty inexpensively and wrap my current intake pipe with this mesh for additional filtration.

    I'll keep you all posted. Thanks for reading.
    Last edited: May 29, 2018
  6. 7474

    7474 Member

    Dec 8, 2008
    I know this is old but.....

    I use the Sure-Flo SCS2 self-cleaning strainer. Just started this year and can’t recommend it enough. I actually use 2 at a time on my intake from the lake. Use a Goulds Irrigator GT15 to pump off my lake.

    Best price I found was here ....

    I went through many filters and strainers and all needed to be cleaned entirely too frequently. With the addition of the SCS2 I haven’t cleaned yet this year. I also use the pump to power 3 fountains in the lake, so the filters get quite a workout.

    I progressed through multiple strainers which I incorporated into my final set-up. I figured I might as well use them since I paid for them.

    Attached Files:

    Last edited: Oct 23, 2018
  7. birchlake

    birchlake Member

    Jan 19, 2012
    Melrose, MN
    7474, thanks for the reply! I have bookmarked the Sure-Flo website and will do some research on it.

    Update on my filter issue and what I have dodne. I started with the Rusco 100 mesh filter. Too tight of filtration though and it clogged up pretty quickly. So then I went with the Rusco 60 mesh intake filter. Worked perfectly. I did wade out and lightly brush it off every 10 days or so but that takes all of 2 minutes.

    With the 60 mesh filter, I am still filtering tighter than the internal filters on the sprinkler heads so those filters stayed clean. I recently blew out my system for the winter and after that, I went around and checked all of those filters and they had almost no sediment on them.

    Took me about a year to get my sprinkler system perfectly dialed in for coverage and filtration. All good now and ready for action come spring!

    Thanks for the help folks...
  8. 7474

    7474 Member

    Dec 8, 2008
    My problem is the pond is very shallow and has a significant amount of floating debris. Especially early in the season before is treated, I couldn’t get more than 10 minutes of run time before the fountain is practically turned into dribbles. This strainer rotates and is essentially pressure washed from the inside out so nothing sticks.

    In addition to not having to clean the lake filter at all is the increased volume of water.

    I had numerous neighbors tell me “I see you got the bigger pump. I can tell by how much higher the fountains are compared to last year.”

    I’ve made the mistake of leaving the 3 fountains on all day/night and the volume of water/height of spray didn’t change in 12+ hours plus of running them.

    Glad to hear you found a system/set up that works for you. I know what a pain it is trying to find a solution. As you can see from my photo, I went from a 2” foot valve, to a 2” strainer basket, to a 3” strainer basket before I finally found my solution. My mesh solution was simple window screening wrapped around the strainer baskets because the holes were so large.

    The SCS2 isn’t perfect, but it’s as close to perfect as I’ve found.
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