Hydroponic Gardening with Deep Water Culture

by Tyler
(Manchester, UK)

First of all, I would like to congratulate you on your website! I spent several hours trawling the net for clear and concise information on hydroponic gardening with only limited success, until I found your site. It's easy to navigate and contains more information than I was able to get from other sources. Now my questions…

I am looking to install some kind of hydroponic system into my small poly tunnel, but I am limited by two factors. First, there will be occasions when I can not go ever day, most days will be fine, but occasionally ill and have to miss a day. Secondly, I have no power or means of getting any there. I was originally considering either a deep water culture or wick system, but from your comments I am edging more towards the deep water system now.

Unfortunately, however, I will not be able to provide any aeration of the water (unless you know of a passive way of doing this). Is there any way in which I could minimize the detrimental effects this may have. For example, if I was to use a deep water culture system with a substrate that promotes better air flow would this help? Thanks, Tyler.

Answer: Tyler- The success of a deep water culture system (DWC) depends on a few things, each contributing to the overall dissolved Oxygen levels in your nutrient solution and the availability of the Oxygen to all of your plants. The first thing is to keep the hydroponic nutrient solution as close to 68-72 degrees as possible. Cool water is capable of holding more dissolved Oxygen than warm water.

So, you will have many more problems with fungus, plant viruses, and roots dying for lack of Oxygen if you let the water get too warm. One solution is to place the nutrient reservoir on a cold cement floor....but this solution only works if you are growing in a basement. Another strategy would be to bury the nutrient reservoir at least partially in the ground, thereby using the natural geothermal cooling of the Earth to keep your nutrient solution from getting too warm. Either way you will want to keep the reservoir in the shade.

With the nutrient solution kept cool, the next thing you can do is to add air bubblers to your hydroponic gardening system. In my response to another visitor, I discuss using DC power as a backup for things like air pumps and small water pumps. These type of systems use low voltage, and can also be used with a small (and therefore relatively affordable) solar panel to keep your 12 volt battery topped up. This would provide just enough power to keep a deep water culture system running without any problems.

The third thing you will need for the success of your system is a small 280-480 GPH water pump. The pump is placed strategically somewhere in the DWC system to ensure the water is constantly circulating. This prevents "dead spots" in your hydroponic system by moving and mixing the nutrient solution to prevent pockets of low Oxygen or low nutrients (as a result of metabolism in and around the roots).

If no power is to be had and a solar/DC power source cannot be put in place, then I recommend using a combination hydroponic system. The deep water culture part of the system would hold the nutrient solution and make nutrients and water available to your plants, but the majority of the roots of your plants can be grown in a number of different types of grow media in containers placed just above the nutrient solution. A good wicking material, like nylon rope, can be coiled evenly through each plant container with enough rope hanging out the bottom of each container to "wick up" nutrient solution to your plants once the containers are in place.

The wick part of the system would provide moisture and nutrients to each container, while allowing them to maintain plenty of Oxygen within the root zone of each container. For media, I recommend using equal parts perilite and vermiculite. Straight perilite might also work very well, and would be more reusable. Using plain vermiculite is not recommended, as it breaks down and compacts over time (making it harder to reuse as a grow media).

This should give you some great ideas of where to start with your hydroponic gardening project Tyler....I hope this helps, and Happy Growing!