How To Avoid Algae In Hydroponics (Expert Advice)

If you’re running a hydroponic system at home, you’ve probably seen some algae in your reservoir. But if it’s not taken over your entire system and turned into green slime, then it’s not really an issue. 

Hydroponics is still an emerging industry, so there are still tons of things we don’t know about growing plants with water and nutrients. 

While I don’t pretend to be an expert on all things hydroponics (I’m just a hobbyist), this guide will hopefully help keep your plants healthy while also keeping algae at bay!

How to Prevent Algae from Growing in your Hydroponic Unit
Preventing algae growth in hydroponics requires monitoring and controlling light exposure, pH balance, and water quality.
Regular cleaning and maintenance of hydroponic equipment is essential for preventing algae growth and maintaining a healthy growing environment.
Manually removing algae and using an algaeicide or hydrogen peroxide solution can effectively treat algae growth in hydroponics.
Additional resources such as articles and guides are available for learning more about preventing and managing algae in hydroponics.
Checking your hydroponic system regularly for signs of algae growth and plant health is crucial for maintaining optimal growing conditions.

What Is Algae In Hydroponics?

  • You might think algae is just a plant, but it isn’t. Algae is actually a type of bacteria, or microorganism—or even slime or fungus.
  • So what’s the difference between an organism and a microorganism? Well, for one thing, an organism lives outside your body; a microorganism lives on your body!
  • You know how you sometimes see plants in your aquarium? That’s because there are lots of different types of algae that live on plants and grow with them together!
  • Algology refers to the study of algae—and if you want to learn about algology (the study), check out Wikipedia!

To prevent fungus growth in your hydroponic system, make sure to regularly clean and sanitize your equipment. Check out our guide on how to avoid fungus in hydroponics for more tips on maintaining a healthy growing environment.

How Does Algae Form In Hydroponics?

Algae is a form of plant that grows in water. It can be found in natural bodies of water, such as lakes and ponds, but it’s more commonly seen in the aquarium industry.

There are several species of algae that can grow in hydroponics systems, including blue-green algae and black brush algae. 

While these are considered to be unwanted forms of algae by most people (because they’re unsightly and can cause problems with plant growth), there’s no need to panic if you find them growing on your system—they’re actually quite beneficial for plants!

The presence of these types of green slime indicates that your plants have enough light and nutrients available at their disposal.

Avoid Slow Moving Water

Algae in hydroponics can be a big problem. If you’re new to growing plants in water, the best way to avoid algae is to ensure that your water is moving at a fast enough pace. When the water is stagnant, or slow-moving, it creates an environment where algae can grow and thrive.

One of the most common problems in hydroponics is root rot, which can be caused by various factors including poor water quality and insufficient oxygen levels. Learn how to detect and prevent root rot by reading our guide on how to avoid root rot in hydroponics.

Use Minerals, Not Salt

The main reason you should not use salt in your hydroponics system is because it will kill your plants. Salt does not provide any nutrients to the plant and only causes damage when used as a nutrient source.

 Minerals are natural, can be easily obtained from the earth, and do not cause any harm to your plants. They do contain everything that the plant needs for growth and development.

Avoid Stagnant Water & Air Bubbles

Finally, you should avoid stagnant water and air bubbles. Stagnant water means that there are no changes in temperature or circulation of the solution. 

This can happen when you add new water to your reservoir but don’t change the old solution for some time afterwards. 

Air bubbles can also cause problems for your plants because they slow down proper circulation of nutrients throughout their roots, which leads to root rot and other problems. To avoid stagnant water and air bubbles:

  • Make sure that your system is properly sized so that it can handle all of your plants’ needs at once without causing any overfilling issues (this means having too many pumps/filters/etc., not too little)
  • Never let one plant’s nutrient solution get above another’s level, especially if they’re sharing a reservoir (you may have known this already)

Maintaining the proper pH level is crucial for your hydroponic plants’ growth and overall health. Check out our guide on how to bring pH down in hydroponics for tips on achieving the optimal pH range for your system.

Ensure Good Ventilation, If Using Tanks With Lids

For tanks with lids, ensure good ventilation.

Ventilation is one of the most important steps you can take to prevent algae growth in a hydroponic tank.

 It will help keep your plants healthy and thriving by circulating air throughout the tank, which helps remove any excess moisture and CO2 buildup that may be causing an environment that’s conducive to algal growth.

If you’re using tanks with lids (which I don’t recommend), it’s important to make sure they’re vented properly so that there’s enough airflow inside your system without letting too much light into it as well!

Regularly Wash Growing Pipes Or Tanks

One of the easiest ways to avoid algae in your hydroponics system is to make sure that you regularly clean any pipes or tanks. 

All you need is a small brush and some bleach water, which will kill off any algae that may have started growing inside the pipes or tanks. 

You can also use a hose to rinse them out, but be careful not to spray too much water into any electrical components or other sensitive areas.

If there is no way for the cleaning solution and/or rinsing water to drain from these places within your system, we recommend using a bucket at least once per week and throwing away any dirty mixture that accumulates there (make sure not to throw away any parts of your system by accident!).

If you’re interested in growing plants indoors using hydroponics, our guide on how to build a hydroponic garden indoors is an excellent resource to get you started. Our guide covers everything from choosing the right equipment to selecting the best plants for indoor growing.

Keep A Lid On Your System (If Applicable)

When it comes to keeping algae at bay, there is one simple thing you can do: keep a lid on your system.

Keep the lid on your system to prevent dust and debris from entering. If there are any particles floating around in the air, they will find their way into your water supply and start growing on everything on plants, roots, walls and floors.

Keeping a lid on your system also prevents water evaporation which can lead to nutrient deficiencies in plants. 

If you think about it for a moment (which I’m sure you do!), this makes sense because if there is no water for roots or leaves then no nutrients will be able to get absorbed either!

Finally, keeping a lid on your hydroponics setup keeps out pesky mosquitoes that may come along looking for somewhere cool and dark where they can lay eggs! 

Just another reason why having an enclosure over top of whatever kind of container/systems used inside means less harmful bugs getting into places where they shouldn’t be allowed access

Add Hydrogen Peroxide To Your Water

Hydrogen peroxide is a chemical compound made up of two oxygen atoms and two hydrogen atoms. In its pure form, it is colorless and has an odorless scent. Because it is an oxidizer, it can be used as a disinfectant or sanitizer to kill bacteria and fungi. 

Hydrogen peroxide has been used for many years in medicine to prevent wound infections when cleaning a cut or abrasion on the skin. It’s also a common ingredient in many household cleaners because of its ability to kill bacteria when diluted properly with water.

Mixing one part hydrogen peroxide with nine parts water creates what’s known as “3% H2O2 solution” a dilution that can be used as a natural pesticide against algae by simply spraying directly onto affected plants!

Are you new to hydroponics? Our guide on how to build a hydroponic garden for beginners is a great place to start. We cover the basics of building a hydroponic system and offer tips for maintaining a healthy growing environment for your plants.

Have A Proper Filter And Air Pump In Place

A good way to avoid algae is by having a proper filter and air pump in place. This is the most important step, so it bears repeating.

The air pump should be attached to the top of your grow tent, not on the floor of it. The reason for this is that if you put your pump on the floor, you’re likely going to suck up dirt and dust particles from beneath it as well as from around it and those are very bad things for plants!

As an extra precaution, try not to put your air pumps directly above or below plants (unless they’re trained vines). 

If there are no other options available for positioning your ventilation unit then make sure that any debris surrounding or near where you plan on placing them gets cleaned up first so that nothing gets sucked into either end of its filtration system before being pushed out again into open space (which could cause blockage).

Equipment for Preventing Algae in Hydroponics

Air pumpProvides oxygen to plant roots and helps prevent algae growth in water and growing medium
Air stoneIncreases oxygen diffusion and water circulation, preventing stagnant water and reducing algae growth
Submersible filterRemoves organic debris and suspended particles, reducing nutrient breakdown that can lead to algae growth
UV filterKills algae cells and spores, preventing their spread in hydroponic systems
Horticultural sprayerProvides a fine mist and improves humidity control, reducing water evaporation and creating a less favorable environment for algae growth

Clean Everything Properly Before And After Each Grow Cycle

To keep algae spores and bacteria out of your hydroponic setup, it’s important to clean everything properly before and after each grow cycle. This includes the growing medium and pipes, as well as any tanks or reservoirs in your system.

If you’re using a cleaning agent (like vinegar), make sure to use it on all surfaces—including drainage holes! You don’t want anything getting into the water supply that could potentially harm your plants later on down the road.

Even though algae is technically a part of nature’s ecosystem, it isn’t welcome in hydroponic systems because it will consume nutrients meant for more useful plants like tomatoes or strawberries instead. 

To prevent this from happening at home, always keep both the water reservoir itself as well as its filter clean using regular cleaning agents like vinegar or bleach solutions; these products can also help remove harmful pathogens from other parts of your system including pipes leading up towards where seeds might germinate inside growing beds themselves.

Cleaning Tips for Hydroponic Setup

When to CleanWhat to CleanHow to Clean
Before Each Grow CycleGrowing medium, pipes, tanks, or reservoirsScrub with a solution consisting of hydrogen peroxide and white vinegar
After Each Grow CycleAny remaining plant debris, pipes, tanks, or reservoirsUse a commercial-grade cleaner or an eco-friendly solution made of water and vinegar
WeeklyGrow room, lights, fans, and other equipmentWipe down surfaces with a damp cloth or use a commercial-grade cleaner
MonthlyPumps, heating and cooling systems, and air filtersDisassemble and clean parts or use a commercial-grade cleaner

Avoid Any Kind Of Dirt And Dirt Particles From Entering Your Water Reservoir

Avoid any kind of dirt and dirt particles from entering your water reservoir. Dirt can contain microorganisms that are harmful to your plants, as well as minerals that can cause your plants to develop deficiencies. 

If you want to keep your reservoir clean and free of dirt, use a filter and a pump to keep the water moving.


We hope you’ve learned a lot about algae in hydroponics! At the end of the day, we really believe that it can be avoided if you follow these simple tips and watch out for any signs of algae. 

If you do see some green stuff growing on your plants or pipes, simply remove it immediately with an anti-algae solution or water change. 

If this doesn’t help enough then contact us at [email protected] and tell us all about your system so we can help out too!

Further Reading

Here are some additional resources to learn more about preventing and managing algae in your hydroponic system:

Why Farm It: Algae in Hydroponics – This article discusses the causes of algae growth in hydroponics and offers tips for prevention and management.

Hydroponic Way: 6 Easy Steps to Prevent Algae Growth in Rockwool – Learn how to prevent algae growth specifically in rockwool with this step-by-step guide.

General Hydroponics: How do I deal with algae build-up in my hydroponic system? – This FAQ page from a hydroponic supplier offers advice on how to prevent and control algae in your hydroponic system.


How does algae grow in hydroponics?

Algae in hydroponics typically grow due to a combination of factors such as high humidity, warm temperatures, poor water quality, and insufficient light control.

What are the consequences of algae growth in hydroponics?

Algae can compete with your plants for nutrients, light, and oxygen necessary for growth, leading to poor plant health and yield. Moreover, algae can clog your system and promote the growth of harmful bacteria.

How can I prevent algae growth in hydroponics?

To prevent algae growth, maintain proper nutrient balance, control light exposure, clean and maintain equipment regularly, and adjust environmental factors such as temperature and humidity.

How can I get rid of algae in my hydroponic system?

To treat existing algae growth, remove as much of the algae as possible manually, then use an algaeicide or hydrogen peroxide solution to kill remaining algae.

How often should I check for algae in my hydroponic system?

Regularly check your system for algae growth at least once a week. However, if you notice any changes in water color, moisture levels, or plant health, check immediately and take appropriate action.