How to Check and Fix Light Leaks in DWC Cannabis? 

Hey DWC growers, have you ever found yourself in a battle against root rot? It's like the nemesis of hydroponic gardening, sneaking up on your plants and causing chaos. It’s the boogeyman for your DWC cannabis plant.

But here's the kicker — did you know that light leaks can make this nightmare even worse? 

Yup, they're like the sidekick that amplifies the villain's power. In this guide, we're delving into the shadowy realm of DWC root rot and shedding light on why those tiny leaks are such a big deal. 

In this article, you’ll learn everything you need to know about how light leaks cause root rot, how to fix this issue, and how to make your DWC cannabis setup lightproof. You'll also learn how to detect light leaks in the grow tent. 

Read on to know more. 

What is Deep Water Culture or DWC?

Image Credit - @Boradan

Deep Water Culture (DWC) is a technique for cultivating cannabis where the plant's roots are suspended in a solution that's rich in nutrients. 

Unlike growing in soil, DWC offers everything, including nutrients, oxygen, and water directly to plants. Needless to say, hydroponically grown cannabis has the potential to grow faster as the plants get exactly what they want.

If you’ve never heard of DWC, here’s a quick overview of how it works:

Hydroponic Setup: DWC systems typically involve a reservoir containing the nutrient water and the plants are placed in such a way that their roots dangle directly into the solution using either a pot or another supporting structure.

Nutrient Mix: The nutrient solution plays a role in supplying nutrients to the plants. It usually comprises water combined with a balanced mix of macro and micronutrients necessary for cannabis growth. Maintaining the right pH of the solution is key to ensuring optimal nutrient absorption by the plants. For hydroponic plants, the pH should be between 5.5 to 6.5 for optimal absorption. 

Oxygen Supply: A significant benefit of DWC is that it provides oxygen to the roots. Oxygen is delivered through air stones or other aeration methods, guaranteeing that the roots receive oxygen for respiration. This process encourages root development and aids in preventing problems like root rot.

Lighting Needs: Plants rely on light to produce energy, so you need to purchase grow lights with appropriate intensity and spectrum. As always, you can go with an 18/6 cycle where the plants get 18 hours of light and 6 hours of darkness. 

Temperature and Humidity Management: Similar to other techniques of cultivation, you'll need to maintain proper environmental conditions even for DWC systems, which means that you'll need to maintain temperatures between 70 to 85°F (21 29°C) during the day and slightly lower at night. Controlling humidity levels in the growing area will help prevent issues like mold and mildew.

Why Are Light Leaks a Problem for Cannabis Plants?

Cannabis is not averse to problems, but few problems are as dangerous as root rot. This problem is common and also goes by the name Slimy Roots. Essentially, it is fungi growing on the roots. 

While root rot may only occur on the roots, it can affect the entire plant. This is because the fungus starts growing on the roots and prevents them from absorbing the nutrients effectively. This leads to severe nutrient deficiencies in the plant. 

Once the problem develops, the symptoms start showing up on the entire plant. You’ll spot symptoms like uneven growth, loss of vigor, nutrient deficiencies, wilting leaves, reduced rot mass, damping off, etc. If it’s not fixed in time, root rot can kill cannabis plants. 

When root rot attacks the plants, it starts showing up on the roots. It forms a creamy brown or white layer with a shiny film on the roots’ surface, hence the name slimy roots. The fungi can also produce a nasty earthy aroma which your DWC cannabis should never smell of. 

Where does light come into play here? The most common cause of root rot in hydroponic and DWC cannabis plants is light leaks in the root zone. When roots are exposed to light, the fungi spores — if present — start breeding on the roots and turn into slimy roots in a matter of days. 

Light encourages this; even a small light leak can cause this problem. Therefore, you must check and fix any light leaks in your deep water-culture cannabis plant. 

How to Check for Light Leaks in DWC Setups?

Image Credit - @fjore3009

This is where things get tricky. Unless you have a waterproof camera with excellent picture quality and a remote to control it, you can’t check for light leaks from within the reservoir or the root zone. So, what do you do? 

Be creative. Every DWC system is unique, so what might work for someone may not work for you. Begin by inspecting the joints and panels on your hydroponic system and see if there are any gaps in it. Even small gaps, like ones on the lid, for example, can cause light leaks. 

You can also get nitty-gritty and start looking at things from below to check for any light leaks. In some cases, a light leak can come from something as little as a pinhole between the pot insert and the reservoir. 

Light leaks pose risks to cannabis plants in DWC systems as they can disrupt their growth cycles and decrease yields. You can avoid these issues by detecting these leaks early so the plants can focus on proper growth and development. 

How to Check for Leaking Light in the Grow Tent?

Sometimes, there could be a problem with the grow tent itself. When there’s a light leak, it can interfere with the plant’s growth. So, here are effective methods for spotting leaks in your growing area:

Visual Examination

Thoroughly inspect your growing space during both day and night periods. Check for any areas where external light may enter the space such as gaps around doors or windows, openings in ventilation ducts, or sealed electrical cord entry points.

Conduct a darkness test

You can conduct a darkness test to identify leaks efficiently in your grow tent. There's nothing too complicated about this. All you need to do is block off your growing area temporarily and remove all light sources you can spot. If you notice even a tiny hint of light, you must block it. 

First, turn off all lights and equipment in the growing space. This includes the grow lights, fans, air pumps, and any other devices that emit light or electricity. Also, shut the doors and windows tightly and cover vents or openings to create a sealed environment.

Once you've sealed off the growing area and switched off all the equipment, wait a bit so your eyes adjust to the darkness. It might take a few minutes. Don't use your mobile or any device that emits light, including flashlights. 

After your eyes adjust to the darkness, you can start examining the area for any signs of light leaking in. Even tiny specks of light could indicate leaks that require your attention.

Make sure to check for any areas where light might be coming in through cracks, gaps, or poorly sealed spots such as doors, windows, ventilation ducts, or electrical outlets.

Remember to inspect everything slowly as it may not be obvious at first but light could be seeping in through the tiniest of cracks and you may miss it. 

Once you've identified some leaks, make a mental note of them so you can fix them when the lights are on. Or, you can mark the area with a marker to close the leak later. 

Once you're done with identifying all possible leaks, switch the lights back on. Now, it's time to take action to seal off the leaks. You can seal leaking points using a caulk or some weather stripping. 

Infrared Cameras

If you're very serious about blocking light leaks, infrared cameras can help. These specialized cameras pick up on radiation that objects emit based on their temperature. 

Anything with a temperature above 0 emits radiation with the intensity correlating directly with its temperature. By detecting and displaying this radiation, infrared cameras generate images that show temperature variances in the area.

Light leaks typically occur where there is a rise in heat emission within the growing space. When external light seeps into the cultivation area it can be absorbed by surfaces like walls, floors, or other equipment, which makes them heat up. An infrared camera can detect this localized spike in temperature, making it easy for you to identify sources of leakage.

To spot leaks using an infrared camera, carefully scan the entire growing space, especially focusing on spots that are prone to light leaks. Pay close attention to the walls, ceilings, floors, doors, windows, vents, and any other possible entry points for light. Move the camera slowly and systematically, capturing heat images of the surroundings from several angles.

While scanning the growing area with the camera, analyze the heat patterns and temperature differences shown in the images. Try to identify areas with spikes in temperatures compared to their surroundings as it might indicate that there's light infiltrating there. Look out for hotspots as there may be light leaking there as well. 

By matching up images taken by the camera with the layout of the growing space you can pinpoint exact spots where light leaks might occur. Concentrate on areas showing temperature irregularities and mark them for reference so you can seal them easily.  

Once you spot any light leaks, make sure you fix them promptly. You can also use blackout curtains as they block light. 

Light Meter

Readings from a light meter offer data that can help you evaluate how light is distributed within your growing area. If you measure the intensity of light at several points in the grow room, you'll be able to identify any discrepancies that usually indicate light leaks. 

However, remember to get a light meter specifically designed for horticultural purposes. Also, purchase a light meter from a trustworthy brand as it needs to be accurate. 

Next, you'll need to Identify spots where you'll take light intensity readings. These spots should cover the perimeter and areas with potential leaks such as doors, windows, vents, and electrical outlets.

Place the meter at each measurement point and record the light intensity readings. Make sure to hold the meter at a consistent height to ensure accurate and comparable measurements. Keep a record of all readings for analysis.

Next, compare the obtained light intensity readings from various areas to identify drastic discrepancies. Areas with lower intensity compared to their surroundings signify that there could be light leaking there. 

How to Lightproof Your DWC System for Cannabis?

Image Credit - @Chi_Town_White_Boy

There are two steps for ensuring your DWC system is lightproof and protects the roots without any light leaks. The first step comes when you’re building the system. So, if your system is already ready, make sure the materials you’ve used are correct; if not, replace them. 

If you are starting with deep water culture to grow cannabis, consider using these materials for building the setup:

• Use thicker tubs that are sturdy and filter light properly — always go for thicker tubs when possible 
• Stick to black tubs and plastics that block light effectively compared to pale-colored plastics and tubs 
• If the plastic panel is adequately thick, even pale plastics and tubs can be lightproof but do your due diligence before using them 
• Cover the lid with reflective material that will not only reflect the light but also the heat away from the roots 

Generally, you don’t have anything to stress about for light leaks if you are using dark and thick plastics or materials around your DWC system. 

How do you know if something is lightproof? Simply use your phone’s flash. Turn it on point it at the plastic and look at the other side; if you see light, it is not lightproof.

How to Lightproof Net Pots?

Image Credit - @Stork

As mentioned earlier, one of the most common areas where light leaks occur in deep water culture cannabis is the net pot part. So, you need to ensure the holes for the net pot are completely covered and lightproof. 

You’ll be surprised to know that, sometimes, light can even pass through clay pebbles if you’re unlucky enough!

Before we proceed, always remember to avoid cheap or thin materials like paper towels or plastic plates — they are never lightproof. Plus, they don’t last very long. 

Instead, stick to materials that are tried and tested by other growers and have shown promise in their DWC steps. Some of the most popular materials you can use to lightproof your DWC for cannabis are as follows:

• Neoprene Inserts for Net Pots 

What do you know — you aren’t the only one facing this problem! You can find neoprene inserts for net pots that are specifically made for this job. So, instead of directly adding clay pebbles to your net pots, you first insert these neoprene inserts. 

They are made to stop light and come in a variety of sizes. Sometimes, some brands can be more expensive than others. But if you want to save some cash, you can make your own inserts with neoprene sheets and scissors. 

Regardless of the option you choose, always make sure the neoprene inserts you use are of the right size. Otherwise, they can still let some light pass through or impact your plant’s growth. 

• Net Pot Covers

Similar to neoprene inserts, you can also purchase net pot covers that are specifically made for this purpose. They also go by the name of root guard lids or light guards. Essentially they are covers that reflect the light instead of letting them pass to the roots. 

• Tape

If you still have some light leaks around your DWC setup, you can even use black tape to cover them up. Electrical tape works great here; you can also use other opaque tape options. Just tape the hole up and you’re good to go. 

• Lightproof Tubing 

Another way of preventing light from getting to your DWC water is by using lightproof tubing, preferably black. 

How to Treat Root Rot in Cannabis Plants?

If you’ve discovered light leaks in your DWC setup, you may have also encountered root rot. So, here’s a quick recap on how to fix root rot in your cannabis plant. Follow these steps.

Treat the Plant

1. Remove from Medium: Take the plant out of its growing medium.
2. Root Rinse: Gently rinse the roots under clean water to remove any slime.
3. Trim Damage: Use sterile scissors to cut away any damaged root parts.
4. Hydrogen Peroxide Bath: Submerge the roots briefly in a 3% hydrogen peroxide solution.
5. Dry Time: Place the roots on a tray and let them air dry for a couple of hours.

Rinse the System

1. Discard Nutrient Solution: Dispose of the old nutrient solution.
2. Bleach Rinse: Flush the entire hydroponic system with a 10% bleach solution.
3. Fresh Rinse: Rinse the system thoroughly with fresh nutrient solution.

Replant Your Plant

1. Nutrient Boost: Add beneficial nutrients and bacteria to the medium for root recovery.
2. Prevention Check: Monitor reservoir oxygen levels and room temperature to prevent future issues.
3. Replant: Carefully replant the cannabis in the clean hydroponic system.

Following these steps will effectively treat root rot and support your plant's recovery.

Summary: How to Check and Fix Light Leaks in DWC Cannabis 

There you have it, DWC cultivators — the solution to light leaks and root rot in hydroponic cannabis setups. By taking the time to seal those leaks and safeguard your system, you're not just protecting your plants but giving them the best shot at thriving. 

Remember, a stitch in time saves nine when it comes to root rot, so don't underestimate the power of lightproofing. Your cannabis plant roots are sensitive to light even under ideal conditions, so it’s crucial to ensure your DWC reservoir is light-proofed.

Moreover, if harmful organisms within the tank are exposed to heat and light, they can rapidly reproduce. If left unaddressed, these organisms can lead to root rot or unsightly algae blooms, posing a serious threat to your plant's health and growth.

With a bit of vigilance and proactive action, you can keep your garden flourishing and root rot at bay. Happy growing, fellow cannabis enthusiasts!