Frequently Asked Questions―Hydroponic Systems
Hydroponics is becoming increasingly popular among commercial and hobby growers for many reasons. Simply put, hydroponics is growing plants without soil. As long as there are nutrients in the water supply, soil is not essential for plant growth. Since this discovery in the 19th century, hydroponic growing has evolved into different types, with many benefits over traditional, soil-based cultivation. With the right setup, hydroponic growing is a cost-effective method of producing high-quality crops with maximum yields. Since this form of growing is becoming so popular, many of our customers have had questions on how to get started, and what they need to succeed. Here is a list of some of the more common questions we’ve had.
1. What is the simplest system to start out with?
Dutch buckets are very easy to start with because you don’t have to worry about recirculating the water. Also, with a Dutch bucket system you can start off small and expand from there. With NFT channels, the channels themselves can be a bit difficult to handle. If you’re just starting out and have a small space, we recommend Dutch buckets, otherwise NFT channels will work well.
2. What is the difference between Dutch buckets and NFT?
In a Dutch bucket system, plants are grown in a media, like perlite, and a nutrient solution is provided to them from a drip system that is run on a timer. Water is not supplied continuously and it is not recirculated in this type of system. Any unused water is drained away. In nutrient film technique, or NFT, plants are grown in a channel. The channels are set up to create a slight slope towards one end. The water is usually recirculated and a nutrient solution continuously runs through these channels bathing the roots.
3. How deep is the liquid nutrient flow through the channel in hydroponic trays?
In the channels, the water is usually about 1/8″ deep. A better way to measure is by flow rate. You want the water to flow at a rate of four cups per minute. To measure the flow rate, run the system, hold a measuring cup at the end and time for one minute. Adjust the system to increase or decrease flow based on your results.
4. Are there ever problems with roots clogging up the channels?
Not that we have seen. Because you are constantly running a stream of nutrients over the roots, they don’t need to spread out to seek the nutrients they need.
5. How do you prevent the Dutch bucket drain hole from clogging up?
You can use a piece of screening, fine mesh, shade cloth, weed mat or a geotextile fabric—anything that will allow the water to still flow through without a problem.
6. What are the problems with recirculating water in Dutch bucket systems?
You can set up a system to recirculate the water, but it is more involved. There is much more plumbing and testing that needs to be done. You would need to collect the runoff from the system and the water would need to be tested for nutrients. Each time the water runs through the system you will end up with different nutrient deficiencies based on what the plants absorbed. Once the water is adjusted to the proper nutrient levels, it can be recirculated back to the reservoir tank and run through the system again.
7. Can you use NFT channels for vine crops?
Yes. We recommend using the GT70 channels, since they are wider and deeper than other channels. They provide enough aeration for vine crops like tomatoes, cucumbers and squash.
8. What are the lengths of your NFT channels?
Our channels come in 10, 12 and 20 foot lengths. We also have joiners that allow you to extend the lengths or you can cut the channels to fit the size needed for your application. We recommend using a saw with a fine blade when you cut the channels. You can also cut the lids to fit any system size you want. If you want us to make custom channels for you (outside of the stock lengths), you must order a set minimum.
9. What does NSF certified mean?
NSF stands for the National Sanitation Foundation. Certified means that this system is made with food-grade recycled vinyl.
10. Can you grow different plants in the same channel at the same time?
Hypothetically yes, however each type of plant has their own nutritional needs, so it will be difficult to regulate the proper mix of nutrients. We don’t recommend this method unless you’re an experienced grower.
11.Can the systems be maintained without electricity? Can they be run by gravity only?
You could probably do this by putting the channels on a slope, but keep in mind you still need a way to pump the water through the channels. If running the pumps through another energy source such as solar or battery power is an option, then you can. Otherwise you will need electricity to move the water through the channels.
12. Does the nutrient water flow continuously?
In the NFT systems, the nutrient water flows continuously at a rate of approximately four cups per minute. When you first get started, the easiest way to measure the rate of flow is to hold a measuring cup at the end of the channel, turn the system on and see how much water you accumulate over one minute. The water does not flow continuously through the Dutch bucket systems; those systems run on a timer. Depending on what your crop is, you’re going to find that the timing is different. It can also be dependent on the temperature of the greenhouse and how quickly the plants are transpiring.
13. Do we have to drill the holes in the lids?
That is up to you. We offer the lids with no holes if you want to drill them yourself or we offer predrilled lids. If you decide that you want to grow something that requires larger spacing than what we provide, that is no problem. You can order the lids without predrilled holes.
1. Are there special seeds for hydroponics?
No, you can use almost any kind of seeds you want, as long as they are clean. If you are going to grow tomatoes, we would recommend using an indeterminate variety. That way the plant will keep producing flowers as long as you are growing.
2. What is the optimal temperature and humidity level for hydroponics?
You want to keep your water temperature between 68°F and 70°F. This is the range that will make the nutrients most readily available to the plants. Humidity is usually around 40% to 60%, but it depends on what you’re growing.
3. What is the optimum pH for hydroponics?
The optimum pH for plants is somewhere between 5.8 and 6.2. Any higher or lower pH can prevent nutrients from reaching the plants causing nutrient lockout. You may see signs of plant stress and mineral deficiencies, which can result in yellowing of the leaves, among other symptoms. It is important to maintain a proper pH level so the plants end up healthy and marketable.
4. Does growing hydroponically affect the taste or flavor of what is grown?
5. Can root crops be grown hydroponically?
Yes they can, however, as a beginner they may be quite challenging. Some more experienced growers do grow root crops hydroponically, but it is not something you should tackle unless you have experience.
6. How long will a single plant continue to produce before having to replace the plant?
Just like everything else, plants have a life expectancy. It depends on the plant. For instance, if you’re growing tomatoes that are either determinate or indeterminate varieties, once they stop producing, they need to be replaced.
7. What material is used to hold plants vertically and solidly in the channel?
That’s your choice. You can use rockwool, or we also offer something called Sure to Grow® which is a recycled plastic that is chemically inert and pH neutral. Both are good options; you just need something solid to hold the roots so they can grow out into the nutrient solution.
8. What lighting is best?
It depends on what you’re growing. The best thing to do is find out what the footcandle requirements are for the crop you’re growing and utilize that as a starting point.
9. Do you need to be concerned with any of the problems other large-scale growers have seen such as outbreaks of bacteria or disease?
Yes, there are problems that can arise in hydroponic growing. One of the things with hydroponics that is very important is the environment. You need to keep everything as clean as possible. You don’t want to have an outbreak in your system if you can help it. We recommend that you clean your channels on a regular basis with a mild bleach solution. Without soil, you won’t run into problems with soil-borne diseases. However that’s not to say you won’t run into problems with botrytis or insects. If you’re growing outside and using side or curtain ventilation, you need to have some kind of insect barrier to prevent insects from getting into your plants.
Nutrients & Pollination
1. How do you test for proper nutrient levels?
pH levels can be tested to determine if the nutrients are being absorbed by the plants. It is best to use an electrical conductivity (EC) or a total dissolved solids (TDS) meter on a regular basis. In our system, we recommend placing the meter directly on the outside of the tank and recording your measurements on a daily basis. This will tell you whether you need to add more nutrient solution or more water and at what ratio into the channel. Keep in mind that ratios are crop specific.
2. In general, how often does the fertilizer solution have to be replaced in a NFT system?
It’s hard to say. Not only is it crop dependent, but it also depends on the size of the system you are running.
3. What is the best way to recycle the used nutrient solution when you need to change it?
You can use it on your house or garden plants. Most of the nutrients will already have been used by the plants in the system, so expect the nutrient solution to be less concentrated than when you first used it.
4. How do you pollinate crops if they require it?
You can either pollinate by hand every other day during the necessary 4 to 6 day period by taking pollen from the male part of the flower to the female part or you can bring in beneficials. Bees or wasps that pollinate the flowers are examples of beneficials.
5. Has anyone tried to use a bee hive in their greenhouse with hydroponics to help with pollination?
Yes, you can actually rent a bee hive for this purpose. They will send it to you by mail. Once the hive arrives, release the bees in the greenhouse. When they’re done, they will go back into the hive and you can mail it back. If you don’t want to hand pollinate or if you have a very large system, you can bring in bees without a problem.
Is there an important question we missed? Let us know and we will do our best to find the answer.