How to Get Rid of Mold in Hydroponics6 min read




Mold… that fuzzy, unwelcome guest that can sometimes pop up in our hydroponic gardens.  While hydroponics is an awesome way to grow plants, the constantly moist environment can be a magnet for mold, which can harm your plants and is generally just a bummer to deal with. But don’t worry!  Getting rid of mold in hydroponics is totally doable.

First, we need to understand what we’re up against. Mold can show up in different ways – you might see white or grayish fuzz on your roots , on your growing medium, or lurking around your reservoir. A musty smell is another telltale sign.

The good news is, with the right approach, you can kick mold to the curb and keep your hydroponic garden thriving. This guide will walk you through how to get rid of mold in hydroponics – we’ll cover cleaning up the current problem and, most importantly,  how to keep those pesky spores from coming back!


 Identifying Mold in Hydroponics 

Before we start waging war on mold, let’s make sure we’re targeting the right enemy.  While the fuzzy white or gray stuff is the most obvious visual sign, here are a few ways mold might try to sneak into your hydroponic garden:

 Fuzzy growths:  

  • The classic appearance of mold. Look for it on roots, growing media (like rockwool or clay pebbles), on the surfaces of your reservoir, or even on plant stems.

 Musty smell 

  • Does your hydroponic setup have a damp, earthy smell? That could be a sign of mold lurking out of sight.

 Slimy textures 

  • If your roots or other parts of your system feel slimy, it could be an early indication of mold taking hold.

Important: Mold comes in different varieties, some more harmful than others.  While this guide provides general strategies, if you have concerns about the specific type of mold in your system, taking a sample to your local plant nursery or agriculture extension service might be a good idea.

 How to Eliminate Existing Mold 

It’s time to roll up our sleeves and tackle that mold head-on! Here’s your battle plan:

 Safety first 

  • Before handling moldy materials, protect yourself with gloves and a mask. Mold spores can be irritating, especially if you have allergies.

 Isolate the enemy 

  • If mold is on specific plants, carefully remove them and temporarily place them in quarantine (like a bucket with clean water) to prevent spreading spores to other plants.

 Cleaning time 

 System cleaning: 

  • Thoroughly scrub your reservoir, pumps, tubing, and any other components using a diluted bleach solution (follow product instructions for safe ratios) or a hydrogen peroxide solution.

 Growing media 

  • Badly infested growing media (like rockwool) should be discarded.


  • If the plant itself is worth saving, gently rinse its roots under clean water to remove visible mold.

 Fungicide (optional) 

  • For severe infestations or stubborn mold, consider a hydroponic-safe fungicide.  Choose a product specifically formulated for hydroponics and follow the directions carefully.

Important Note: Always clean your equipment thoroughly between working on different plants to prevent spread.

Terracotta Composting 50-Plant Garden Tower by Garden Tower Project

 Preventing Mold in Your Hydroponic System 

Now that we’ve banished the current mold problem, let’s make sure it stays gone! Here are the key strategies for keeping your hydroponic system mold-free:

 Air circulation 

  • Good airflow around your plants and in your growing area helps prevent moisture buildup that mold loves. A small fan can make a big difference.

 Light control 

  • Algae thrive in light, and unfortunately, they can create an environment that encourages mold growth. Keep your reservoir covered and minimize light exposure to your nutrient solution.

 Cleanliness is key 

  • Regularly clean your equipment, remove any dead leaves or plant debris, and  sanitize surfaces. A clean environment is less hospitable to mold.

 Temperature matters 

  • Warmer water can encourage mold growth. Aim for water temperatures within the optimal range for your plants, generally on the cooler side as tolerated.

 System savvy 

  • Some hydroponic systems, like those with many nooks and crannies, or with areas of stagnant water,  are more prone to mold issues.  Keeping your system design as simple and streamlined as possible can help.

 Additional Tips 

  • Beneficial bacteria to the rescue: Adding beneficial bacteria to your hydroponic system can outcompete harmful organisms like mold and create a healthier overall environment.  Look for products specifically formulated for hydroponics.
  • Be vigilant: Regularly inspect your plants, reservoir, and growing media for any signs of mold. Catching it early makes it much easier to deal with!


 To Sum it Up 

Mold might seem like a formidable opponent, but remember, you have the tools to keep your hydroponic garden lush and thriving. By understanding how to eliminate mold and, importantly, how to prevent it in the first place, you can minimize its impact.

Remember, consistency is key!  Regular maintenance, careful observation, and a few preventive measures will go a long way in ensuring your hydroponic plants flourish without those pesky mold spores. Now get out there and enjoy your healthy, mold-free garden!

 Check out our friends at Lettuce Grow: 15 minutes of maintenance per week is all this system requires.
The Farmstand Is Your Self-Watering, Self-Fertilizing Solution for an Easy to Grow Harvest

 FAQ: Dealing with Mold in Hydroponics 

Q1: Is all mold in hydroponics harmful?A1: While most molds you’ll encounter in hydroponics are undesirable, some might be less harmful than others. However, it’s best to address any mold growth to prevent potential problems and maintain a healthy system.

Q2: Can mold make me sick?A2: Some molds can release spores that irritate the respiratory system or trigger allergies. Always use gloves and a mask when handling mold, especially if you are sensitive.

Q3: Will removing visible mold fix the problem?A3:  Unfortunately, just removing what you can see isn’t enough. Microscopic spores can remain, so cleaning your system thoroughly and addressing the root cause are crucial to prevent it from coming back.

Q4: Is bleach the best cleaner for mold?A4: Diluted bleach is effective for sanitizing equipment, but hydrogen peroxide is another good alternative. Choose whichever is readily available and follow the product’s safety instructions.

Q5: My plants were badly affected by mold. Can they be saved?A5: It depends. If roots are mostly healthy and the plant is otherwise strong, gently clean the roots, repot in fresh medium, and monitor it closely. Severely damaged plants may not recover.

Q6: Can I add beneficial bacteria to an established system?A6: Yes! Beneficial bacteria can be added at any time to boost your system’s health and create a less welcoming environment for mold.

Q7: Are some hydroponic systems more prone to mold than others?A7: Yes. Systems with stagnant water zones, intricate components, or lots of hard-to-clean surfaces might be more susceptible.

Q8: Will keeping the water colder prevent mold altogether?A8: Cooler water temperatures can help discourage mold, but it’s not a foolproof solution.  Maintaining optimal water temperature while focusing on other preventive measures is the best approach.

Q9: Will a stronger nutrient solution fight mold?A9: No, using too much nutrient solution can actually create imbalances that could worsen problems.  Stick to the recommended dosage for your plants.

Q10: I cleaned everything, but mold came back quickly. What went wrong?A10:  There may be an underlying issue like inadequate airflow, light leaks reaching your reservoir, or consistently warm water temperatures.  Revisit the prevention strategies to see if adjustments are needed.



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