13 Deep Water Culture Tips for Hydroponics (Achieve Massive Harvest)

Although deep water culture (DWC) could be the easiest hydroponic system to use, some still fail to achieve a good harvest. Believe me, my first trials on deep water culture were also epic fails! But I have discovered several secrets that led me to successfully grow veggies and herbs up to this day.

Here are practical tips for massive harvest from deep water culture:

  1. Use an opaque reservoir
  2. Insulate the reservoir
  3. Use air pump
  4. Choose plants wisely
  5. Don’t submerge roots fully
  6. Have an EC meter
  7. Check pH
  8. Top off and flush
  9. Take care of the roots
  10. Disinfect nutrient water
  11. Distance LED lights properly
  12. Plan for power outage
  13. Clean the system

Knowing these secrets has made my hydroponic journey worth it. Like you, I also asked questions like: What is the right pH? How to know if I am providing the proper nutrients? What is the best water disinfectant? So let us dive in and answer those questions today!

How to Achieve Big Harvest in Deep Water Culture

A proper provision of favorable environmental conditions such as water, pH, temperature, sunlight, nutrients, and sanitation is the root of having a bountiful harvest from deep water culture hydroponics.

For you to have specific knowledge of each factor, let us discuss the following 13 tips for using deep water culture.

1. Use an Opaque Reservoir

An opaque reservoir ensures the health of the nutrient water, which is the foundation of deep water culture hydroponics. Pest incidence and high water temperature are prevented when opaque reservoirs are used.

Algae infestation is one of the biggest problems in deep water culture. We can observe algal growth when sunlight enters the nutrient water reservoir. Why? This is because an abundance of sunlight and nutrients favors their growth and reproduction.

To counter this, make sure that no amount of sunlight peeks through your hydroponic solution. You can do this by purchasing an opaque reservoir or wrapping the reservoir in white cloth.

I have mentioned a while back that using an opaque white reservoir also prevents high water temperature. The next tip will provide you with more ways to counter this problem.

2. Insulate the Reservoir

Nutrient water temperature above 72°F is a breeding ground for bad microorganisms. Coating the reservoir with white paint or using reflective insulators are wise actions to keep a normal water temperature.

Maybe you are wondering, why white? Well, the color white reflects light. Therefore, white-coated reservoirs will not absorb the heat along with light.

This is the reason why you can always see styro boxes as deep water culture hydroponic systems. Using them takes advantage of the fact that they are white in color and also an insulator. Thus, a cheap and effective choice for hydroponics gardening.

Another great option are reflective insulators like this which you can buy on Amazon. They reduce the radiant heat gain—thereby preventing heat from being absorbed by your hydroponic system!

3. Use an Air Pump

Air pumps provide dissolved oxygen to the nutrient water. Having an oxygen-rich hydroponic solution prevents plant diseases such as root rot.

Deep water culture can be classified into active and passive. Active deep water cultures are systems that utilize air pumps; while passive deep water culture hydroponic systems do not.

Although we can also harvest veggies and herbs in passive deep water culture, adding an air pump can increase your harvest and also ensure plant health.

However, if you do not have the budget to add an air pump yet, I will also reveal a secret for passive deep water culture in tip number 5!

4. Choose Plants Wisely

Grow leafy veggies on deep water culture systems with more capacity like hydroponic styrofoam boxes; while fruiting veggies and herbs are best grown in solo hydroponic buckets.

Another aspect that you need to consider is planting efficiency. To illustrate this, let me ask you a question. Would you grow a head of lettuce in just one deep water culture bucket?

Resource-wise, that is impractical! Imagine harvesting just one lettuce head in a bucket that you provided with oxygen, nutrients, and care. This is the reason why you need to choose your deep water culture system wisely.

If you are growing a fruiting vegetable like peppers, eggplant, and tomatoes, one bucket would suffice. Because from that one plant in a deep water culture bucket, you can harvest several fruits!

Whereas hydroponic styro boxes come with many slots—some have 4, 6, 9, or even 12! These boxes can house several leafy veggies such as kale, bok choy, and lettuce.

Maybe you are thinking, can hydroponic boxes also support the fruiting vegetables? The answer to that is yes! If you want even more harvest, you can absolutely use this for fruiting veggies as well.

5. Do Not Submerge the Plant Roots Fully

Immersing the whole plant root system will lessen oxygen supply—leading to drowning and root rot infestation.

Proper Setup for Passive Deep Water Culture Hydroponics
Proper Setup for Passive Deep Water Culture Hydroponics

Remember that root rot cannot proliferate in an oxygenated environment. With active deep water culture systems, having air stones and stronger water pumps gives more oxygen to the hydroponic solution.

But in the case of passive deep water culture, having some space for air between the roots and nutrient solution provides plant roots a room to breathe.

6. Have an Electric Conductivity Meter

Too much nutrients will lead to toxicity that could also harm the plants. Electric conductivity (EC) meters are used to monitor nutrient concentration in a hydroponic solution.

It is important to ensure that you are not providing your plants with too many nutrients especially because they will sit in the nutrient solution for a long time. When exposed to a high concentration of nutrients, plants might have damaged roots, resulting in a nutritional lockout.

With this, you must maintain the proper electric conductivity for your nutrient solution. For instance, leafy veggies like lettuce need a lower electric conductivity (1.4 mS/cm) than fruiting veggies, like tomato (2.0-5.0 mS/cm).

High electric conductivity readings would cause water stress in plants. When fertilizer is too high, the first symptom to look out for is wilting. On the other hand, if the plants have low electric conductivity, or are undernourished, they might appear floppy and light green.

7. Check pH

Acidic or alkaline nutrient solution is not healthy for plants. Thus checking pH regularly would be a helpful action for every hydroponic gardener.

To do this, let the nutrient solution sit for at least 2 hours. Afterward, dip the pH meter in the hydroponic water. A value of 6.0 is the ideal pH while 5.5-6.5 is the acceptable range.

Best pH and Electric Conductivity for Plants
Best pH and Electric Conductivity for Common Hydroponic Veggies and Herbs

8. Top Off, Change Water, and Flush

Giving the hydroponic solution new water every 2 to 3 days and replacing them fully every 1 to 3 weeks would ensure nutrient water quality. Before harvest, flushing can also enhance the taste and texture of the harvest.

Topping off means adding water to your system to account for the lost water because of evaporation, transpiration, and absorption of the plants.

Changing water must be done because your plants consume nutrients and water daily. Along the process, the strength of the nutrient solution decreases.

Furthermore, flushing is replacing the nutrient solution with plain water days before harvesting. This is done to enhance the harvest quality indices such as taste and texture.

9. Take Care of the Roots While Changing Water

When changing water, make sure that the roots are not damaged. Wounds can be points of entry for plant diseases that can harm the plants.

Remember that the roots are the most critical part of your plant. Why? Because they are the ones absorbing water and nutrients needed by your veggies and herbs in order for them to grow.

Thus, when changing your nutrient water, it would be helpful to have a location to lay the bucket’s lid. By doing this, you let the plant’s roots dangle which prevents them from getting wounded.

You can also have an additional reservoir or any container to place your plant on while you are changing your water.

10. Disinfect Nutrient Water

Use food-grade hydrogen peroxide in treating hydroponic water.

While your plants are growing, ensuring plant health is vital. Using disinfectants such as hydrogen peroxide would be helpful to make sure that your hydroponic nutrient water is clean.

By incorporating hydrogen peroxide in your hydroponic water, you are decreasing the chance of root rot infestation. To do this, 2 to 3 teaspoons of food-grade hydrogen peroxide must be added for every gallon of water.

11. Distance LED Grow Lights Properly

Keep the light-emitting diode (LED) growing lights 6 to 12 inches away from the plants. Too little distance between the lights and plants can cause leaf burns.

This tip is useful for those gardeners growing indoors.

Most of the time, we tend to place the grow lights so close to the plant itself. But, the problem with this is the excess heat. This heat could cause leaves to curl and not function properly.

When leaves do not function at their best, the plant’s food-making process is also affected. This will further lead to yellowing, wilting, and worse, plant death.

12. Plan for Power Outage

Lessen the water level of the deep water culture hydroponics in cases of power interruptions. This will give the roots temporary access to oxygen from natural air.

In active deep water culture systems, the air pump needs continual power to function. Therefore, a power outage can harm your plants.

Of course, we have a simple solution for this! Remember that If the power goes out, what you need to do is to lower the reservoir’s water level halfway. Through this, more roots are exposed to oxygen while still having access to the nutrient water.

However, this will not stop your plants from being stressed. Nevertheless, it is absolutely helpful for survival. Just remember to turn the air pump on, once the power is back!

13. Clean the System

A clean hydroponic system, including the nutrient water and gardening tools, is an essential practice in ensuring a bountiful harvest.

Make sure that all tools and components of your hydroponic system are clean from planting to harvest!

A Beginners Guide: Hydroponic Sanitation & Sterilization

Cleaning your whole system after every growing cycle is for the best. Proper sanitation will decrease the chances of plant-pathogen dispersal across growing seasons.

As food growers, we must put a premium on this aspect since our number one concern is the safety and cleanliness of our harvest. Remember, human health must be our priority when growing fruits, vegetables, and herbs for consumption.

Summary of How to Achieve Big Harvest in Deep Water Culture

Environmental conditions such as water, oxygen, pH, nutrient concentration, temperature, pathogens, and cleanliness must be considered to achieve massive harvest in deep water culture.

To ensure this, we must be knowledgeable about management practices. Some of these include maintaining water temperatures below 72°F, ensuring oxygen access, checking electric conductivity and pH, water and light management, root care, planning in the case of a power outage, and proper sanitation.


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