Run to Waste
This is essentially a non-re-circulating active system that is usually a drip irrigation set up.
This method is commonly used for large scale commercial hydroponics. Run-To-Waste works by the nutrient solution running into the growing media from a single reservoir via an irrigation system and drippers, sprayers or sprinklers. Ideally there needs to be a certain amount of run-off (about 25%) on a daily basis, as this helps to refresh the media content continually. This method nearly always uses timers.
The advantage of run-to-waste systems is that nutrient levels remain consistant with every feed, as does pH and EC. Also, in the case of plant disease, there is a reduced risk of contaminating all of the plants in the system. Checking and monitoring the pH and EC of the run-off will give a good indication to how plants are growing.
However on the downside, salt build up at the roots could occur with retained nutrient in the media. Flushing with water intermittently can help reduce this. Responsible disposal of the nutrient run-off is important.
Ideal nutrient for this type of growing is VitaLink Hydro MAX Grow /Bloom and CANNA Hydro Vega/ Flores.