Deep Water Culture is a method of growing crops with their roots directly submerged in a nutrient rich, highly oxygenated solution. DWC tends to be well suited to one or two pots and more frequent nutrient changes are required. RDWC is a very similar method, but constantly recirculates the solution and is well suited to multiple pots.
A water tank can be connected to both DWC or RDWC systems. The tank contains PH and EC adjusted solution. It is drip fed to the system and maintains optimal solution levels as the plants use the solution in the system. Dependent on your requirements you can use the top off reservoir to correct any movement in EC/PPM readings or PH.
The ideal nutrient solution temperature is between 18-20 degrees. At this temperature it is far less likely your plants will contract a root disease. When nutrient solution rises above 20 degrees the plants are unable to assimilate the oxygen as effectively, the risk of anaerobic respiration in the root-zone is increased leading to Pythium and other bad news! The things to look out for and prevent are brown slimy roots that have an unpleasant smell to them. You will see the health of your plants deteriorate fairly rapidly should you have root problems.
To avoid such issues you could consider installing a water chiller. You should always over estimate the size and capacity of chiller that you purchase. Chillers can be fitted to systems in a range of ways; the most common uses the return pump to recirculate the nutrient solution.
When placing young plants in your system it is likely that you will be using a net pot to hold a small amount of medium to secure the plant. It is advisable that you put a 1-2inch layer of clay pebbles or “grow stones” at the base of the net pot. A barrier of non-wicking medium will prevent constant moisture being drawn from the pot below. If you allow Rockwool or coco mediums to touch the water in the system, you will encounter stem rot because the stem will not be able to dry out adequately.
When using organic nutrients or additives in your RDWC system it is especially important that you perform thorough cleaning and sterilisation of the system between crops. This may include measures such as replacing pipework every 6 months. You can also use products such as H202 in order to ensure your system is properly cleaned and free of unwanted pathogens.
During growth and bloom cycles it is recommended that you perform regular full change outs of the water in your system. You will need to do this every 1-2 weeks to ensure that the plants have the correct nutrient profile available.