Algae

Algae is inevitable in any aquarium. As long as you're keeping anything alive in water, you’re going to have some algae—it’s simply not possible to maintain a sterile environment and still support life. The key is to make your microbiome work for you, not against you.

Algae, in and of itself, isn’t harmful to aquatic life. The one major exception is when it starts to grow directly over your live plants and blocks out light. In that case, yes, algae can interfere with photosynthesis and stress or even kill your plants. But beyond that, even the infamous black beard algae is harmless—it might not be pretty, but it won’t hurt anything.

In fact, algae is a natural part of a healthy tank. It’s a food source for many aquatic species, from snails and shrimp to certain fish like Otocinclus or Siamese algae eaters. Some types of algae can even play a beneficial role in water quality, absorbing excess nutrients just like aquatic plants do.

The appearance of algae usually points to one thing: an imbalance. Whether it's excess light, too much nitrate or phosphate, or inconsistent CO₂ levels in a planted tank, algae tends to thrive where something is slightly out of whack. But here's the interesting part—algae helps correct those imbalances. It takes up excess nutrients and brings the tank back toward equilibrium, much like a safety net. When you see algae, especially in small amounts, it’s often a sign that your system is maturing and learning how to self-regulate.

In fact, algae usually won’t even show up in noticeable amounts until your tank is close to being fully cycled. That makes its appearance almost a rite of passage. And while it can be tempting to scrub every inch of the tank clean, it’s important to remember that a little bit of algae is a natural part of a stable ecosystem. Your tank isn’t sterile—it’s alive.

It’s also worth noting that most beneficial microbes stay invisible. They’re doing all the work in the background—breaking down waste, cycling nitrogen, stabilizing the environment—without making a mess. Algae is just the visible tip of that microbial iceberg. It’s not a failure. It’s a sign that life is thriving.