As with ordinary farms apply for growing businesses discharge standards for fertilizers and pesticides. Grow as clean as possible and at the same time as many return water recirculate the task. Investigated which substances may be for plant growth. Harmful in the irrigation water.
The critical limits were tested with measurement series with a bio assay (Fytotoxkit). Sodium hypochlorite, as a widely used fumigant, showed growth inhibition at a concentration from 30 mg /L on. The use of this disinfectant in crop rotation requires carefully rinse. The growth inhibitor Alar (daminozide) used in floriculture showed growth inhibition from 45 mg/L on. This requires attention during a shift to the cultivation of vegetable plants. In the solutions containing humic acids or organic coconut particles also at the highest concentrations on no growth inhibition occurred. The coloring of the water may affect the operation of a UV-disinfector. Organic matter can be a source of bacterial and fungal growth. Finally, the effect of a surfactant in new rock wool was tested. At concentrations that were higher than is used in practice no negative effect was found.