There are two basic types of hydroponic drip systems, Non-recirculating and recirculating [recovery drip systems]. Of course there are many variations of each type but theses are the 2 basic ones.
The recirculating drip system reuses the nutrient solution. It is collected in a small reservoir and recirculated back over the media. Recirculating systems are considered to be more efficient by some in that it does not waste solution, but it has multiple drawbacks in comparison to simple drip systems.
Cycle timers are not all that expensive and are used to precisely adjust the drip flow. Flushing the solution and growing media is still required periodically to avoid nutrient build up over time.
The water in the reservoir also needs to agitated and moving to prevent heavier and lighter minerals from separating in which case the heavier ones will fall to the bottom and not be present in the drip delivery.
A slow draining medium is needed, Perlite/vermiculite or Rockwool work well, Organic media such as peat or coconut coir also work but sometimes add to the issue of clogged drippers.
Drip systems become clogged due to particles from nutrients and organic matter that build up in the emitters. Systems that use organic nutrients and media are more prone to clogging. A blend of Perlite and vermiculite works very well, some growers also blend it with coconut fiber [coco coir] or peat moss. Perlite is fairly inexpensive but doesn't retain water that well. Vermiculite retains water so when blended with perlite the two compliment one another and make a good hydroponic media for drip systems. A drawback to perlite is that emits an unhealthy dust [to humans] that also contributes to drip clogging, some growers add additional filtering for this reason.
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