From our friends at HowToGrowMarijuana.com:
Most people interested in how to grow marijuana end up studying hydroponic systems. Indoor hydroponic growing under grow lights allows you to control the environment. You can grow in all seasons. Hydroponic technology allows the cannabis grower to achieve consistent harvests of quality marijuana.
But hydroponic systems are not without their problems. Here are some common issues that arise for hydroponic cannabis growers. Good planning, good hygiene and a few tricks will help you resolve each problem.
1. Clogged Hydroponic System
Depending on the type of system you have, clogs can be a daily issue. Drip systems and spray systems (like aeroponics) are especially susceptible.
The Problem: Material (algae, bits of plant debris, etc.) gets stuck and the system can’t function properly. It is common in spray and drip set-ups because these use high pressure pumps to push nutrients through small openings that are easily clogged.
The Fix: You have two main options to avoid excessive clogging.
- Use nutrient and pre-filters. These will help protect your system from clogs. They will need to be cleaned or replaced regularly, and do not eliminate clogging altogether.
- Choose a different hydroponic system. Using a simple continuous flow or ebb and flow system will save you the hassle of dealing with frequent clogging.
2. Leaks in a Marijuana Hydroponic System
Any plumbing set-up is liable to develop leaks at some point or another. Like clogging, leaks are more likely in high-pressure hydroponic systems.
The Problem: Leaks are messy and wasteful. At best you lose valuable nutrient solution and end up with a wet floor, while at the worst your plants dry out and suffer irreparable damage.
The Fix: The most common hydroponic leaks are in stab fittings and drip or spray emitters that fall out of place. You can also get leaks due to root growth in a flow system. The root take up too much space, causing water to back up and overflow. Avoid leaks by:
- Use a low pressure pump in a NFT or DWC
- Get an extra-large nutrient reservoir (big enough to hold all the water in the whole system.
- Use large pipes that will allow sufficient water flow even with lots of root growth.
3. Algae Growth can Kill Cannabis Plants
If you have a hydroponic system you are familiar with algae. It is the green (or sometimes red, brown or even black) slime that appears on your growing medium, clinging to plant roots or stuck to the sides of a container.
The Problem: Algae can harm your plants in many ways.
- Algae consume nutrients intended for your plants.
- It can clog pumps, return channels, drippers and other parts of your system.
- Algae remove dissolved oxygen from the system, which can cause cannabis plants to suffocate.
- Decomposing algae are food for a fungus that can harm marijuana plants.
- Algae growing on plant roots can suffocate the plants.
The Fix: Algae can be hard to control. Most hydroponic growers tolerate it in small amounts. Here are some ways to limit algae in a normal system:
- Keep your nutrients in the dark. Algae need light to grow, so keeping the nutrient solution covered as much as possible will limit its development.
- Dry it out. Algae can’t grow on dry surfaces. You can cover large media beds with plastic film or a layer of substrate to keep the surface dry.
What if your algae problem is really bad? The most common solution is to remove the crop and clean up the entire hydroponic system, starting over with a clean set-up. If you are near harvest or just can’t tolerate the idea of pitching your girls after all your hard work, you could try these solutions:
- Add an algicide product to kill algae. Be careful, as these can also damage root systems, especially those of young plants. Also, algae usually comes right back after these treatments.
- Treat carefully with hydrogen peroxide. Again, use sparingly, and only on older, well-established plants to minimize root damage.
- Add grapefruit seed extract to your nutrients. This seems to work well without harming cannabis plants.
Prevention is always better than treatment. Limiting light in your system is the best way to combat algae.
4. Expense of Replacing Grow Medium
One of the largest costs of hydroponic growing is replacing the grow medium. This can cost upwards of $100 for each grow, even in a small hydroponic system.
The Problem: Many grow mediums can’t be used twice. For example, rockwool has to be replaced for each grow. Coco coir also requires frequent replacement.
The Fix: The best solution is to avoid using disposable growing mediums. You can use reusable mediums like clay pellets or lava rocks. These are commonly used in net pot set-ups.
Some hydroponic systems hardly use any grow medium at all. A DWC or NFT system leaves the roots immersed in nutrient solution.
5. Inconvenient Set-Up
This is a common problem for novice marijuana growers. Some hydroponic systems and set-ups are simply inconvenient to work with day to day.
The Problem: Some systems are difficult to clean, especially if the lid and holes are small. Other designs have unreachable corners or sharp bends that are nearly impossible to get at.
The Fix: Buy or build a sensibly designed system. Some hydroponic systems for sale are advertised as “easy to clean”. They claim easy access to all surfaces.
Any hydroponic system you use should be easy to drain without disturbing the plants. It should drain fully and quickly, so that replacing the solution only takes a few minutes. This will reduce the stress on your marijuana plants.
Keep your Hydroponic Marijuana Healthy
A little advance planning and good cleaning habits will go a long way to keeping your hydroponic marijuana healthy. You should plan to spend a few minutes every day carefully checking your system for signs of problems. You can usually catch leaks or algae overgrowth early this way, when the problems are easier to correct.