In greenhouse practice, growers talk about EC water. EC stands for Electric Conductivity. Very clean water such as distilled water for example has a conductivity of almost 0. The same low EC is caused by reverse osmosis where there are no elements left in the water. Water mixed with fertilizer on the other hand has a high EC as there are many substances (saline) in the water. This water is therefore often called EC water, partly because the EC value indicates the concentration of nutrients. Water with a high EC usually has a high oxygen consumption (BOD / COD) caused by the microorganism that convert ammonia to nitrite and then nitrate. To keep this process aerobic aeration is necessary.