ive never had any problems with the ceramic of the blumats. if they somehow do get clogged, its probably fixable with a soak in some dilute acid.
edit:
Dani8538 said:
also i have found the the water are very hard and contains also very high cal' that can damage (block) the ceramic of the blumats
i just realized we might be talking about different products. doesn't blumat also make a product that essentially wicks water down through the cone itself?
when you mention being concerned that the ceramic will get clogged, im assuming you are reffering to that product, as opposed to the product that acts like a small tensiometer.
the tensio meter product that actually opens and closes a small pinch valve should not be veunerable to carbonate blockages within the ceramic. they DO have a tendency; and i mentioned this above,to form a small clog at the pinch point where the blumat controls the flow of water through the dripper tubing.
however i must again mention ive NEVER had a blumat clog completely. when they kink or get partially blocked they tend to just drip at a reduced rate.
they are really an ingenious solution to irrigation, but only on a small scale.
some golf corses and high tech agriculture centers actually use something very similar. they basically use a set of tensio meters at different depths set out in the field to be irrigated. they are mated with vacuum sensors that detect a water deficit conditions and then trigger an irrigation cycle.
imo this is by far the best way to irrigate crops. a tensiometer is much better than a crude rain sensor/humidistat thermostat combo used by many.