How to Choose Filters for Micro-Irrigation
The outlets of drip tape and micro spray tape are very fine, so even a little sand, algae or rust in the water will clog them. The filter is the "first gate" of a micro-irrigation system — whether it is properly installed directly decides how many years the system lasts. This article explains the three mainstream filter types clearly, so you can choose right the first time.
1. Why Filtration Is a Must
Drip emitters usually have flow channels only about 1mm in diameter, and micro spray tape orifices are only 0.6-1mm. Once suspended sand particles, microorganisms or chemical precipitates get in, they wedge in the channels and cause clogging. So in the head unit of every micro-irrigation system, a filter is standard equipment, not an option.
2. Three Filter Types Compared
| Type | Working Principle | Main Things Trapped | Typical Precision |
|---|---|---|---|
| Sand filter | Water flows through a sand/gravel bed and impurities are trapped by the sand layer | Sediment, organic impurities, algae | Suited to poor-quality water sources |
| Disc filter | Multiple stacked discs with grooves trap impurities | Particulate impurities | 120 mesh class |
| Screen filter | Filtration through a screen | Particulate impurities; secondary fine filtration | 100 mesh nylon / stainless steel screen |
3. The Safest Way to Combine Them
- Poor water quality (pond or river water, high sediment load): trash rack at the intake → settling pond → sand filter at the head → screen/disc filter at the field inlet — two levels of protection;
- Better water quality (well water, tap water): a 120 mesh disc filter or 100 mesh screen filter at the head is enough;
- Fertigation: install the filter after the fertigation device where the line enters the pipe network, so impurities in the fertilizer solution never reach the lines;
- Zone supply with multiple laterals: add a small screen filter at each zone inlet so every zone can be serviced independently.
4. How to Read Mesh Numbers
"Mesh" means the number of openings per inch — the higher the mesh number, the smaller the openings and the finer the filtration. Common equivalents: 100 mesh ≈ 0.15mm, 120 mesh ≈ 0.125mm. A practical range is 100-120 mesh: too coarse and it will not catch impurities; too fine and it cuts flow and needs frequent cleaning.
5. Maintenance Essentials
- Screen/disc filters: periodically remove the cartridge and rinse it with clean water; replace a damaged screen promptly;
- Sand filter: backwash by pressure difference (flush when the pressure drop between inlet and outlet exceeds 0.05MPa);
- Check the inlet and outlet pressure after every fertigation and irrigation event — a noticeably bigger pressure drop means it is time to clean.