Deep water culture

Deep water culture (DWC) is a hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient rich, oxygenated water. Bubbleponics is a related method of plant production that involves a top-fed Deep Water Culture system. A more accurate definition for the acronym DWC is Direct Water Culture. Direct Water Culture can be performed in deep or shallow water.

Traditional Methods & Information

Traditional methods favor the use of plastic buckets with the plant contained in a net pot suspended from the center of the lid and the roots suspended in the nutrient solution. An air pump powered aquarium airstone oxygenates the nutrient solution; if sufficiently oxygenated, the plant roots can remain submerged indefinitely. Once the plants are ready to flower, the level of the nutrient solution is gradually reduced to expose the roots to the air.

Plants absorb vastly more oxygen directly from the air than from the oxygen dissolved in water. Deep water culture allows plant roots to absorb large quantities of oxygen while also allowing the uptake of nutrients. This leads to rapid growth throughout the life of the plant.

Recirculation Deep Water Culture

Recirculating direct water culture systems (also known as RDWC) use a reservoir to provide water for multiple buckets. Traditional methods using unconnected buckets require individual testing for pH and conductivity factor (CF). This has led to innovations that have seen the removal of air stones in favor of connecting multiple buckets together and recirculating the water. As the water is reintroduced to the bucket it is broken up and aerated with the use of spray nozzles. Constant recirculating oxygenates the water and ensures a good mix of nutrients CF and stabilizes pH throughout the entire system so testing is required only at one point, which would be at the 'Tub' like reservoir. The Deep Water Culture system requires adequate water + oxygen nourishing solution.

The solution is oxygenated (possibly near, or equal to, oxygen saturation) from an air pump combined with porous stones. With this method the plants may grow faster because of higher amounts of oxygen that the roots receive, verses other forms of deep water culture.

Super-saturation of water, i.e., increasing dissolved oxygen (DO) level well above saturation of the source water (ex., DO of 40 ppm [mg/L] at 75'F), is unnecessary for the 'best' plant growth. And has been found to hinder plant growth verses saturated water (ex., DO of 8.4 ppm at 75'F) and slightly-more-than saturated water (ex., DO of 9 ppm at 75'F).

Bubbleponics

The term "Bubbleponics" describes a top-fed Deep Water Culture hydroponic system. Basically, the water is pumped from the reservoir up to the top of the roots (top feeding). The water is released over the plant's roots and then runs back into the reservoir below in a constantly recirculating system. As with traditional Deep Water Culture, there is an airstone in the reservoir to help add oxygen to the water. Both the airstone and the water pump run 24 hours a day.

The biggest advantages with Bubbleponics over Deep Water Culture involve increased growth during the first few weeks. With Deep Water Culture, there is a time where the roots haven't reached the water yet. With Bubbleponics, the roots get easy access to water from the beginning and will grow to the reservoir below much more quickly than with a Deep Water Culture system. Once the roots have reached the reservoir below, there is not a huge advantage with Bubbleponics over Deep Water Culture. However, due to the quicker growth in the beginning, a few weeks of grow time can be shaved off.^[1]

DWC Hydroponic System usage

It is advisable to start this type of indoor cultivation with cubes of rock wool. Once the seeds are germinated in cubes of rock wool, put them into the DWC baskets previously filled with expanded clay pellets. Fill the DWC system with water and fertilizers that are hydroponic specific up to the level of the solution in contact with the base of baskets.

In this way, the clay will be in contact with the solution that will be absorbed by the plants roots. Soon the plant will develop a large root system that will naturally immerse in the nutrient solution. It will not be necessary to maintain the level of nutrient solution to the same level of the base of the baskets, but results will come with a lower level. It is recommended replacing the nutrient solution approximately once a week and wash the container / tank with hot water to remove any algae, mold and salt deposits. Every time you fill the tank, measure the pH of the solution and ensure that its value is between 5.5 and 6.8. Revise with the pH indicator. Constantly monitor the pH. The well-oxygenated and enlightened environment promotes the development of algae. It is therefore necessary to wrap the tank with black film obscuring all light.

References

1. ^ "Growing Cannabis with Bubbleponics". GrowWeedEasy.com. http://growweedeasy.com/high-yield-bubbleponics-technique. Retrieved 2010-09-27.