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I am planning on sucking water from a pond to feed an irrigation line with some sprinklers or drippers (the exact sprinkler/dripper is to be confirmed - but likely something like https://www.mitre10.co.nz/shop/neta-micro-spray-base/p/276967 - "Micro Spray Jets" for use in home gardens or https://www.mitre10.co.nz/shop/neta-adjustable-dripper-thread/p/274935 drippers or similar.

I am wanting to put a screen or filter before the drippers. I did speak the distributor - and while they were helpful they could not advise how fine the screening should be (he did say something about them having a mesh in them). I have a nice, relatively large surface area 250 micron filter I can use - but is this fine enough? (I have found some Pope Poly In-Line barbede filters - but I can't find any specs as to how course they are). I've also seen 130 micron filters - which seem to be a common size - but all the ones I've seen so far suffer from not being transparent - so I can't easily see how dirty it is. I also don't know if 130 micron is small enough.

Any thoughts on how fine a filter needs to be to prevent the sprinklers from clogging up with dirt ?

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  • That's dependent on the type of sprinkler or dripper, particularly the orifices that water (and anything in the water) must pass through. So, there isn't one answer. There are multiple answers which require knowing what the water delivery device is, in detail. If the retailer does not have that information you may need to backtrack to the actual manufacturer to get the details. As for clear filter housings, they tend to cause algae problems...
    – Ecnerwal
    Feb 14 at 14:12

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One Supplier (no endorsement) suggests 80 mesh (177 micron) for "sprinklers and rotors" (think the big ones) 120 mesh (125 micron) for "drip emitters, sprayers, and spray jets" (roughly your case) and 155 mesh (roughly 100 micron, all the charts I can find skip that size) for drip tape.

So your 250 micron (60 mesh) filter might be of use as a pre-filter, but is apparently not of itself suitable for the type of delivery you have planned, in general.

Surface water makes filtration a big issue, and often requires substantial filtration effort & maintenance as the contaminant load is typically high, relative to well water sources. I use a 200 mesh (74 micron) filter on a drip system, but I also expect very little contamination from my well-water source.

Stock advice on monitoring filter performance is to change or clean/flush it at 5-7 PSI (34-48KPa, 0.34-0.48 bar) differential across the filter, which of course requires two pressure gauges but which does not require a clear housing. If you have a clear filter housing I would recommend an opaque cover whenever you are NOT looking at it to prevent algae growth inside it, particularly pumping pond water.

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  • Brilliant answer. Thank you. (The filter housing will live in a shed with no direct sunlight and normally totally dark, so I think it will be fine - but that does help explain why most filters ive seen are not seethrough.)
    – davidgo
    Feb 14 at 19:04

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