Fluctuations outside the desired ranges can lead to nutrient lockout, deficiency or toxicity, which can lead to plant stress or death. The pH of the nutrient solution should typically be maintained between 5.5 and 6.5. During vegetative growth, it is better for the pH to be on the higher end of this range, whereas it needs to be on the lower end of the range during flowering stages. There are numerous online resources which can advise you on the ideal constituents and concentration of a nutrient solution for any plant and growth phase. If you are using a two or three stage nutrient solution, there will usually be guidance included within the packaging or on the bottles.
Generally, I would advise caution with the PPM of the solution. It is usually better to err on the side of making a less concentrated nutrient solution, to ensure your plants will tolerate it. Over time, you can increase the concentration to levels closer to those recommended. It is essential to ensure the roots are submerged into the water solution, yet also make sure that the stem and foliage are exposed to the air. To stay safe, it is recommended to keep around 1 to 1.5’’ of the roots exposed to the air to make sure the stem is sufficiently far from the solution. At any rate, water bubbles will eventually reach these exposed sections of the roots and will prevent them from drying out. This can be done either by conventional means or by using an aeroponic cloner. Aeroponic cloners are quite simple to use and enables easy transplanting of the young plants, as they will have bare roots and can go directly into your deep water culture system.
The best plants that can be grown in deep water culture systems are those that do not need to flower. Lettuce and other herbs are particularly suitable due to the greatly accelerated growth rates which can be achieved compared to soil based cultivation. Kale, chard, collard greens, tomatoes and peppers are all excellent candidates. Building A DIY Deep Water Culture Hydroponics System. In order to build a Deep Water Culture system, you will need: Water container or reservoir Air pump Air hose and air stones for bubble formation Grow nets or baskets to hold the plants Growing media to support the plant in the basket Hydroponics nutrients Equipment to monitor pH and EC of the nutrient solution. The first step is to connect the air pump, the tubing and the air stone. Place the air stone at the bottom of the reservoir, with the tubing going out to the pump, which should be situated close to the reservoir. A good way of suspending the grow nets or baskets is to cut a sheet of Styrofoam to the size of the top of the reservoir. You can then cut holes in this so that the net pots sit securely in these holes. Next prepare your plants by putting them in the grow nets or baskets and secure them in place with your chosen growing media. Next make up your nutrient solution and add it to the reservoir. Finally, put your plants in place so that they sit with their roots well submerged in the nutrient solution. Ideally, you should maintain around 1.5’’ of the roots exposed to the air to avoid the risk of the stems becoming submerged in the water over time. The water solution should have sufficient bubbles to resemble boiling water; these bubbles are necessary to oxygenate the water, to deliver sufficient oxygen to the roots to allow them to remain healthy. The system will need close monitoring for several days after being set up to ensure that the roots are receiving sufficient water, and the pH and EC of the nutrient solution will need to be monitored carefully and adjusted as necessary. In order to introduce dissolved oxygen into the nutrient solution, two aeration techniques are used; namely air bubbles and falling water. Air bubbles can be produced using the joint operation of an air pump and air stones. The air pump delivers air containing oxygen into the water through the air stone. These bubbles can also be formed using an air hose, which will produce a larger number of smaller bubbles. This increases the surface area of the bubbles, which increases the oxygenation of the water. Instead of using air pumps and stones to introduce bubbles, some water culture systems may utilize falling water to aerate the nutrient solution. This is because as water turbulently falls into the water reservoir, it applies downward pressure on the water and allows more oxygen to dissolve into the solution through the exposed surface area.
This technique is, however, quite uncommon for home systems as falling water is more suited to larger scale systems. Optimum Water Level In A Deep Water Culture Hydroponics System. The optimum water level in deep water culture reservoirs depends on the placement of the plants on top of the water surface. The question is, should the plant holders (whether it is Styrofoam or a basket or a lid with holes) be touching the surface of the water or slightly hanging above it? As mentioned earlier, leaving an exposed portion of the roots on top of the water surface is healthy for plant growth to reduce the risk of root rot. It also allows a margin of safety to prevent the stems from becoming submerged. Stems and foliage will not tolerate even well oxygenated water like the roots are able to. The height of the plant above the water surface also depends on the absorption capability of the growing media. If a highly absorbent medium is used, there is less risk of the roots drying out , and it is more acceptable to let the plants sit slightly higher above the level of the water. Hence, the absorption rate of the growing media needs to be considered when deciding the level at which to suspend your plants.
The size of the plant also determines the water level in the reservoir.