Today our hydroponics series is about Deep Water Culture (DWC). Here, the roots are permanently in a nutrient solution enriched with oxygen. The plants are germinated or pre-grown in rock wool and then usually stand in DWC pots filled with hydrocorrels. These hang in buckets filled with nutrient solution and should only be filled so far that the nutrient solution just touches the expanded clay. The hydrocorrels draw the nutrient solution upwards and the root system can develop well. Soon the roots grow out of the pots and hang into the water.
The nutrient solution level is lowered as the plants grow. The roots do not need to be completely submerged, on the contrary, lowering the water level exposes the plant roots more to the air. Cannabis can absorb more oxygen from the air than from the water. Lowering the nutrient solution level therefore has a positive effect on yield and quality.
The nutrient solution should be changed at least once a week and the container/bucket cleaned with hot water to prevent algae, salt deposits and mould. To prevent algae growth, the bucket must be absolutely opaque, no light should fall on the nutrient solution under any circumstances. The pH value must, of course, be checked regularly and continuously lowered from 6.3 to 5.5 during the cycle.
- pH value: reduce continuously from 6.3 to 5.5
In simple Deep Water systems, a net pot is placed in the middle of the bucket lid. In the bucket there is a bubbling stone that enriches the nutrient solution with oxygen through a pump. The water in the bucket bubbles, which is why the Deep Water method is often called a bubbler.
Recirculation Deep Water Culture (=recirculation deep water culture)
More elaborate systems are recirculating , i.e. they consist of a tank that supplies several buckets with water. The advantage is that the pH and EC values do not have to be determined for each bucket individually; checking the nutrient solution in the tank is sufficient. The temperature of the nutrient solution must be kept low (approx. 18-20° degrees) so that algae or disease infestation does not occur. In summer this may mean that further cooling has to be used. Then it is also easier if only one tank needs to be cooled.
DWC systems need sufficient water & oxygen and a precisely adjusted nutrient solution. However, with some expertise, very good results can be achieved relatively easily.
-->more about: Hydroponics, aeroponics, aquaponics - Part 8: NFT
