Clogging of your irrigation drippers could be caused by biological, chemical, or sediment issues
Biological: The clogging material is usually slimy organic material. Soaking the drippers in a dilute bleach solution should clean up biological material (test the drippers can handle the corrosive material first).
If the material is biological, determine where the contamination is occurring (water source, or within the irrigation tanks or pipes). Send in water samples from different locations within the irrigation system to a lab for analysis of total aerobic bacteria counts. Counts higher than 10,000 colony forming units per milliliter indicate a high clogging risk from biofilm.
You will probably need to shock the system with a high rate of an oxidizer (such as chlorine, chlorine dioxide, or a peroxyacetic acid product) to clean the lines. Do not let shock solutions contact your crop. To keep the irrigation lines clean, you could then add a low concentration of a water treatment chemical such as chlorine. With any product, follow EPA label instructions and extension recommendations.
Chemical: The material may look like powder or be gritty and crystalline. Soak drippers in vinegar (low pH) – if this cleans up the emitters then a chemical problem is likely. Send samples of this soak solution, your irrigation water, and the applied nutrient solution (if you use water-soluble fertilizer) to a testing lab to analyze what specific ions are reacting from your water and/or fertilizer. Knowing the specific ions is needed to take action. For example, you may need to inject acid to reduce precipitation of calcium deposits, or oxidize and filter to remove iron and manganese. A shock with a line cleaner is likely to be needed to unclog lines. Do not let shock solutions contact your crop.
Sediment: The material may look and feel gritty. When you soak in warm water, solid particles may drop out. Sediment indicates the need for more filtration, with a finer filter pore size than the emitter size. You may need to blast out lines with high pressure, and use a line cleaner to unclog lines. Do not let shock solutions contact your crop.
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