Algae formation is very common in hydroponic setups and not only can it be an eye soar but harmful to your plant’s growth. Algae is also a living organism and cannot be fully eliminated in hydroponic systems but taking the time to keep it down to a controllable level will do your hydroponic system a favor.
Just like leafy greens and vegetables algae also requires nutrients, water and light to grow. These are all vital for hydroponically grown plants so it only makes sense this very same environment would be suitable for algae growth, only it’s unwanted growth. Once started, algae can quickly form overtaking a system. Take early measures to properly prevent its growth by following a few things when starting your hydroponic system.
Your Container Matters
Take the time to properly buy a growing container that is suitable to block out light such as black 5 gallon storage totes easily found at your local hardware store. If unable to get a hold of a similar item, consider covering your container with packaging paper, newspaper, paper bags, trash bag, paint or spray paint.
Depending on how big your container is, a trash bag or spray paint may be better solutions. However, make it simple on yourself and save yourself the time and suffering. Even paint will flake off onto your plants and scrape off over time to stain surfaces.
In the beginning of my hydroponics journey, I thought it would be cute to paint my mini hydroponic cans with black matte chalk and spray paint but that quickly became a headache and a swear fest. It took too long to dry and when wet, would sometimes smear off.
Make sure to block out the light, and algae growth will be controlled. Currently my favorite methods in blocking out light aside from starting with a proper container are:
1. Aluminum Foil
2. Packaging Paper
3. Soda Can Cooler
These are quick and effective methods and can also easily be removed for cleaning and nutrient checks.
Wet Growing Mediums
We have prevention in our container but what about the surface? On the surface, light is everywhere. What do you do? Know that algae is a spore and can easily travels on the surface and will thrive if the growing medium stays wet. For this reason, I like to let my growing medium dry out once the roots are long enough to reach the nutrient source in a Kratky hydroponic setup. Letting it dry out prevents algae on the surface. This method is not always easy as a simple bump can dampen the medium so the next little thing I like to do is cover the surface with aluminum foil or some black hand cut outs made from folders like shown in the photo below. For larger net cups and larger plants, consider covering the growing medium with clay pebbles.
Cinnamon
There’s probably some cinnamon in your kitchen pantry somewhere. Cinnamon can also be utilized on the surface if you are experiencing some algae growth. Lightly sprinkle it over the growing medium. This method can be effective and smells wonderful however I find it gets a bit messy when trying to spread it in a localized area. It’s worth a shot though, give it a try! Make sure to not overly lay cinnamon into a dense area though. I’ve had small sensitive seedlings die because of using too much.
Cleaning
Practice good habits by properly cleaning your containers and tools and properly disposing your nutrient waste. I like to filter my nutrient waste and then dilute it with water to water my outdoor plants. Follow your local regulations to properly dispose waste. Remember algae itself starts out as spores and can be on tools and surfaces. At the end of a plant’s life, take take time to give your containers and net cups a good soak in diluted bleach and hydrogen peroxide for clay pebbles. I recently purchase food grade 12% hydrogen peroxide and diluted it down to 3% to also spray and clean my work area down.
Although impossible to eliminate in any hydroponic system, consider these tips to help to prevent algae growth in your hydroponic garden.
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