How To Prevent Algae In Hydroponics

by RightFit Gardens | Last Updated: July 27, 2021

In hydroponic gardens, algae are the weed. You will have to keep algae infestation under complete control in a hydroponic system to prevent it from ruining all your hard work. The presence of algae in aquaponic systems is more problematic, but it can also cause problems in hydroponic systems if left unchecked.

When water is exposed to sunlight, algae will grow. It is unsightly when present in small amounts. Water nutrient concentrations are reduced, and oxygen concentrations are reduced. This can lead to a decrease in plant growth and affect pH levels. Keeping the system healthy requires managing algae growth. You can keep your hydroponic system thriving and algae-free by following the tips in this article.

Algae Control in Hydroponics

As you cannot completely eradicate algae, it is crucial to identify and prevent it as much as possible. As a result, cleanings are less frequent.


hydroponics algae preventionUnderstanding what algae are and how it gets into hydroponic systems is the first step in understanding how to prevent and manage algae in hydroponic systems. As well as identifying it, you must also understand what it is. Many simple water plants make up algae. Many types of these plants exist, including pond scum and kelp.

Aquaponic systems provide amounts of algae with all the elements they need to thrive and grow. The appearance of algae can vary based on which strain is growing since algae are groups of organisms. The appearance and color of algae can differ.

Since algae in hydro setups are particularly susceptible, algae can survive in the same systems as plants.


Algae management involves two steps. It is imperative to prevent the growth of algae as much as possible. To protect your nutrient mixture and growing medium from sunlight, prevent sunlight from reaching them. Algae cannot grow without sunlight. To prevent light from reaching the liquid, all parts of the system that hold water or hydroponic nutrient solution must be made from opaque materials.

The potential growth areas won’t be eliminated, however. The dripper or emitter may still develop algae. It is well known that preventing algae formation is impossible, so that most gardeners will accept a few strands of algae here and there. Through good gardening practices, they try to keep it at a minimum. When algal growth becomes too invasive, we perform full cleanings following harvests.

Barley Straw Rafts

Large hydroponic systems benefit most from barley straw mats. On water systems, the rafts float. The chemical released by the decomposition of barley straw inhibits the growth of algae. The process takes a long time. To maintain aerobic decomposition, an abundant supply of dissolved oxygen will be required. Also available for purchase is barley straw extract in liquid form.

In addition to preventing growth, this can result in dead algae. Despite this, you must carefully monitor the dying rate since decomposing algae can lead to oxygen depletion and plant death.


The air carries algae spores, so it is essential to fully clean the growing area, not just the hydroponic setup. A surface such as a wall or lighting system may prohibit them from growing. After some time, they will be carried back into the water by air, reappearing as algae.

You must thoroughly clean everything that comes into direct contact with your system. It is important to clean all pots and pebbles to remove any algae or spores. It is important to use a new or sterile item to avoid contamination with algae or spores.

Thoroughly Clean Your Growing Room

It is imperative that you thoroughly sanitize your grow space if you are growing indoors. When you clean your system, you should take care to remove any spores that are stirred up. So that dust does not fall on clean surfaces.

The air intake filters of the system should be inspected and cleaned. Once the air filters have not been changed, it is easy to forget them when flushing the system. You can also clean the filter if particles fall out of it when the room is being cleaned.

Drain the System

You must remove the old nutrient mix entirely from the system. Your removal method will depend on your system:

For tanks with drains: The water can be let out by simply opening the valve. Ensure that there is a run-off area lower than your tank so you can clean it afterward. Using a sponge and bucket, remove any remaining water in the system.

With pumps: Remove the pump from the tank, taking care not to damage any electronics. You should connect the female connector to the pump’s outlet pipe. Wherever you wish to drain the water, you can place the outlet hose. Remove water with the pump until it is almost dry. After that, use a sponge and bucket to clean up any remaining debris.

Create a Cleaning Solution

One of the following cleaning solutions is needed to clean the parts of the system. It does not matter which you prefer, and each solution is equally effective.

You should remove pumps and air stones.

Checking for algae is necessary. Algal spores can spread quickly, so it’s better to be on the safe side and clean the pool. A buildup of algae can often be seen on the insides of pumps, where it is difficult to see or remove. Make sure that all pumps and stones are cleaned using the chemical solution you choose.

In addition, it is a good idea to check your potting medium and pots at this time. You should treat pumps, pots, and growing media with a peroxide solution. During the cleaning of the rest of the system, these items can soak.

Dispose of hard-to-reach parts and debris.

If an area of the system is hard to reach, it needs to be removed to be cleaned by hand. During this process, check for any broken roots or debris that needs to be removed. Reintroduction of algae might be possible through these carriers. Additionally, they serve as growth media for bacteria and other pathogens.

To soak small components, you can use a bleach bath. The mix must be 1:1 for this. The items must be triple rinsed following the bleach bath to remove all bleach residue.


Choose a cleaning solution that suits your needs and use green scrubbing pads. It is necessary to clean all surfaces showing signs of algae. You can clean the tubing or hard-to-reach areas with bottle brushes. If you see a lime green stain or a gelatinous slime, you must scrub it off. Using a clean rag, wipe these areas after scrubbing them before putting your system back together.

Sanitizing the System

You must add the sterilizing solution to the system. You will have to pour the solution higher than usual if you want to cover the algae-growing area. You can run the system for 4-6 hours. While cleaning conduits and channels, be aware of debris or algae being flushed back into the tank.

Rinsing the System

Remove the cleaning solution from the system. Be certain to remove all debris before flushing with fresh, clean water. For a complete clean, you must triple flush the system after using bleach. Once all the water has been drained, it must be rinsed and flushed one more time. With a clean towel, wipe down the tank and any other visible areas. It is not recommended to use those that have been exposed to algae.

Each harvest requires this cleaning. This will ensure that any trace of algae is eradicated. It will also inhibit other pathogens or bacteria from growing in the system. Use fresh nutrient mixtures when refilling your system, and do not keep your solutions for more than seven days.

Algae Reduction Alternative Measures

You can also reduce the number of algae in your hydroponic system using other methods. In many cases, algae can be killed and prevented using chemical algaecide products. These are unfortunately not suitable for use because they will damage the root systems of growing plants. As a second problem, once algae growth has been suppressed, cleaning up the system requires more effort. Among the other options are:

UV Sterilizer: Sterilizing nutrient solutions with UV light is another method. A plastic or steel cylinder can house UV lights. The nutrients are placed in this system. Using UV light, it is possible to kill algae spores in nutrient solutions and water sources passing around the algae. A tank wall or other surface that already has algae attached to it will not be destroyed by the UV light.

Humic Acid: A mixture of humic acid and water gives the tank a dark color. Because algae can’t grow in the absence of light conditions, they don’t flourish. The water may become too shallow, however, which can increase algae growth.

Grapefruit Seed Extract: This organic algae control method uses grapefruit seed extract. Drinking water, ponds, and lakes have been treated with it successfully without causing any harm to the plants. Upon algae death, the hydroponic solution still needs to be filtered to maintain oxygen levels in the system. Every few days, check for algae growth.

Problems Caused by Algae in Hydroponics

In hydroponic systems, stubborn algae pose several problems. Mechanical problems are the first issue. Almost any surface can support algae growth. It can slither into pipes and pumps in a system, causing clogging and slowing the machine down or even causing it to fail. In the long run, it will cease to function altogether. As it decomposes, it emits a horrible odor.

Algae use up the nutrients in the system to grow, so it depletes them. During this period, biological oxygen demand is created in the system. Plant roots are responsible for absorbing dissolved oxygen from water molecules. The decomposition of algae deprives the sensitive root system of oxygen. As algae decompose, they release toxins. Furthermore, they provide a potential food source for pathogenic fungi. The microscopic fungi can infect plants in the system once they reach a high level and even attract fungi gnats.

How Does Algae Contaminate A Hydroponic System

Algae can into your system through contamination during the process. It is dispersed through microscopic airborne spores that the wind can carry and can be almost everywhere. Algae spores are found in soil or stagnant water and transported via living carriers.

Algae are found in several water sources, including rivers and streams and rainwater storage tanks. Most treatment facilities destroy the algae population, which will slow down an infestation. However, it only takes one spore landing or being brought in with the source water to create an uncontrolled growth and start algae accumulation in your hydro setup.

Once in the system, algae will have everything they need to thrive and spread rapidly. Reducing the light source, water, and nutrients will lessen algae growth but also hurt the plants. Prevention is tough because of spores, but it is the first step in algae management.

The Takeaway

Algae can and will grow unchecked and damage your hydroponic harvests if not managed. It is almost impossible to prevent algae because of its airborne spores. Preventative measures and thorough cleaning between crop yields is the best way to control heavy infestations of algae. So, clean your system now before the effects of algae growth cuts into your crop production.