Marimo Moss Ball Smells Bad? Here's Why!

Marimo Moss Ball Smells Bad? Here's Why!

Ever had that moment when you lean in to admire your marimo moss ball and get hit with a whiff of something... off? It's not just your imagination when your marimo moss ball smells bad or even when the moss ball smells like rotten eggs. 

But here's why this happens...

Stick with me, and we'll get to the bottom of this smelly mystery together, simple and straight to the point.

Here Are The 5 Reasons Why Your Marimo Smells Bad

1. Decay from Within

When you catch a whiff of something less than pleasant from your marimo, it's clear that something's not right inside. This is where our journey begins: Decay from Within. The issue is straightforward—when marimo smells bad, it's often due to improper handling or environmental stress. These factors can upset the delicate balance within your marimo, leading to internal decay.

Here's the science bit: as the marimo's internal structure breaks down, it decomposes. This decomposition process can produce a sulfur-like smell, the very aroma you notice. It's your marimo signaling it's not in its optimal state.

However, our patent-pending brand of moss balls addresses this issue at its core. Thanks to our innovative buoyancy kernel, our moss balls are engineered to prevent internal decay, thus eliminating the root cause of the unpleasant smell. This distinctive feature ensures our moss balls do not suffer from the common problem of decay from within, maintaining their health and freshness without constant vigilance.

2. Poor Water Conditions

When your marimo moss ball smells bad, and it's just chilling in a jar, it's probably yelling for cleaner water. Imagine your marimo's jar is like its mini world. If this world gets filled with invisible gunk, like too much ammonia from leftovers decaying, it's like a trash can that's never emptied. This can make the water stinky, so your marimo moss ball starts to smell off.

Changing the water or ensuring it's the right kind can help greatly. It's like giving your marimo's home a fresh start. So, remember, clean water equals a happy and non-smelly marimo!

Want to make sure your marimo lives its best life? Check out how to choose the best water for it, and say goodbye to bad smells: Learn how to pick the right water for your marimo and keep it smelling fresh!.

3. Bacterial Overgrowth

Bacterial overgrowth is a common reason why your marimo moss ball smells bad. This problem often arises from stagnant water or excess nutrients in the jar, creating a perfect breeding ground for bacteria. These bacteria not only cloud the water but also produce a foul odor.

4. Foreign Algal Contamination

Life cycle of unicellular algae

Algal contamination is another sneaky culprit when your marimo moss ball smells bad. When your marimo's cozy jar gets too much light, it can become a mini greenhouse for unwanted algae. This algae isn't just a sore sight; it can start to decompose, releasing those not-so-lovely odors. Keeping your marimo in a spot with indirect light can help prevent this algal takeover.

Also Read: Marimo Moss Balls vs. Algae: Identifying the Differences

5. Infrequent Cleaning and Maintenance

Neglecting the cleanliness of your marimo's home can lead to a buildup of decaying organic matter, which is a surefire way to end up with a scenario where your marimo smells bad.

Regularly changing the water, giving the marimo a gentle rinse, and cleaning the jar are essential steps in maintaining a healthy, odor-free environment for your green buddy. 

It's not just about keeping things looking good; it's about ensuring your marimo stays healthy and doesn't become overwhelmed by waste that can turn its cozy jar into something far less pleasant.

Don’t know how to clean? Read How to Clean Your Marimo Moss Ball Properly


When your marimo smells bad, it's more than an unpleasant scent; it's a wake-up call to reassess how we care for these unique aquatic plants. This odor signals a need for better understanding and attention to the environment we provide for our marimo. By addressing the root causes of the smell, we can improve our marimo's health and our enjoyment of these fascinating green orbs.

Curious about turning this challenge into an opportunity for growth? Visit Moss Amigos for everything you need to get started, and explore their blogs for deeper insights into marimo care. 


Chen, S. (2015, June 30). What gives the beach that smell? Sulfur-Making algae. WIRED.

Aquatic Life Criteria - Ammonia | US EPA. (2023, June 20). US EPA.

Aquarium Gardens. (n.d.). Aquarium Gardens.

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