How to Get Rid of Algae in Guppy Tank?

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Algae growth is normal in any fish tank and will occur whether you like it or not. Guppies and other aquatic creatures will consume algae in moderate proportions, so these organisms are not really a threat. Unless the situation gets out of hand.

Algae overgrowth is a serious problem that will take over the tank fast. An algae invasion will decrease the water’s quality, leading to poor oxygenation, killing any tank plants, and hurting the fish.

The goal is to prevent algae from taking over their environment, and that requires considering several solutions.

Today, we will discuss how to control algae and prevent them from spreading and suffocating the tank’s flora and fauna.

Prevent and Eliminate Algae in Guppy Tank

To eliminate algae effectively and prevent their spread, you must first learn about their biology. Algae are plant-like organisms that require certain environmental conditions to thrive. Cull those conditions, and they will wither and die. Or at least inhibit their spread and limit their influence in the tank.

Here is how to prevent algae overgrowth and even reverse it when necessary:

– Prevent Overfeeding

Overfeeding your fish will create 2 immediate emergencies:

  1. Unconsumed food accumulating and decaying on the substrate, in the water, and inside the filter
  2. Overfed fish will poop a lot more than they normally would, further burdening the tank’s biofilm

So, overfeeding creates decaying excess food residues and higher amounts of fish waste, poisoning the water. Two things that algae thrive on.

Overfeeding will also impact your fish in other ways, causing digestive problems and increasing the ammonia levels in the water. These are all additional reasons to avoid it in the future.

Guppies will be more than content with 1 to 2 meals per day. This is enough to keep them satisfied and healthy in the long run. Just make sure you only feed your guppies the most that they can eat within 1 minute or so; guppies don’t need much to achieve satiety.

– Reduce Lightning

Algae function via photosynthesis, just like plants. This means that algae don’t fair well in poorly lit environments, which brings us to another interesting point. Artificially-lit aquariums ensure a level of lighting that your fish don’t need.

Guppies only experience moderate lighting in their natural environment, completely different from most bright aquarium lights. The latter are generally for your benefit since they make the aquarium prettier than the guppies.

Acknowledging this fact opens the door to some interesting opportunities, especially if you have artificial plants in your aquarium. Just make the lights less bright or remove them completely and only allow for room-level lighting.

It won’t create any discomfort for your fish but will affect the development and spread of algae.

– Water Changes

Water changes are necessary to preserve your guppies’ habitat in good conditions, improve water oxygenation, and control algae growth. It would be ideal to perform weekly water changes, depending on the tank’s size and how many fish you have.

Just make sure you don’t overdo it. You should only change around 10-20% of the tank’s water at once. Anything more than that can actually become counterproductive.

There’s a saying in the fish-growing business – A too big water change results in too big changes in the water. Massive water changes (30% or more) may cause imbalances in the tank’s microfauna, removing beneficial bacteria that inhibited algae growth. It will also cause wild variations in the water’s pH levels.

These massive water changes will often lead to algae blooming, worsening the very problem you’re trying to solve.

– Use Fast Growing Plants

This is a natural and easy solution to keeping the algae in check. Plants and algae consume the same nutrients since they both fall in the same biological category. This can lead to competition over food and space, which explains why, in nature, algae aren’t as prevalent in plant-filled environments.

Plants will collect nutrients from water, starving the algae as a result. Some types of plants are also more effective at this job than others. If your tank has an algae problem, you might consider using hornwort or wisteria, among other plant species renowned for countering algae.

It’s also worth noting that thriving plants can grow to overtake the aquarium and keep the algae in the shade. Given the algae’s preference for vividly lit environments, the shadier habitat will dramatically affect their spread and growth.

– Vacuum the Substrate

The tank’s substrate is a breeding ground for algae, harmful bacteria, fish waste, and decaying matter, primarily from accumulated food residues. It’s imperative to clean the substrate regularly to maintain the habitat’s balance and counter the algae population.

How often you should vacuum the substrate depends on the aquarium’s size and how crowded the tank is. Ideally, you should probably vacuum the tank’s substrate once every 2 weeks. You may even need to cut that time in half and go for weekly cleaning if your tank holds more fish or they are professional poopers like some species are.

– Use CO2 Systems

This goes back to the lightning problem. Plants need lights to grow, but the brighter the environment is, the more nutrients and CO2 the plants require to support their growth.

This means that using plants to counter algae may not work as intended if you don’t provide plants with all the environmental conditions they need to thrive. This includes lightning as well as CO2 and various other nutrients that they will use to fuel their growth.

To solve the problem, monitor CO2 parameters in your tank, especially if you have a plant-rich environment. If necessary, you can use a CO2 system to boost the CO2 levels, ensuring that your plants remain healthy and growing in the aquarium.

– Use RO/DI Water

RO/DI water stands for Reverse Osmosis De-Ionized water. It’s a mouthful, I agree, but it helps you understand where this type of water comes from. The reverse osmosis process refers to using a filter relying on a micro-membrane to cleanse the water of even the tiniest particles.

These RO filtering units have a 90% rejection rate, which means that only 10% of the water will go through, with the rest being discarded as impure. This is a potent mechanism for purifying the water and helping your tank’s flora and fauna.

This will, again, boost your plants’ ideal conditions, helping plants grow and overtake algae.

However, unlike some opinions out there, RO\DI water doesn’t affect algae. I would even say it functions the other way around, boosting algae growth. This is why I recommend using RO/DI water only if you have live plants in your tank, which will inhibit algae development.

Otherwise, RO water can make your algae problem worse.

– Regular Filter Cleaning

Cleaning the filter regularly will also inhibit algae growth since it removes harmful bacteria that create some of the nutrients that algae thrive on. It will also remove food residues, fish waste, and decaying matter trapped in the filter.

Just make sure you don’t overdo it. The filtering system will harbor a useful ecosystem of beneficial bacteria that the tank needs to preserve its stability. Sterilizing the filter or cleaning it with chemicals will kill these bacterial cultures, hurting the aquarium’s ecosystem.

Use tank water to clean the filter, and don’t go overboard with the scrubbing. Just remove dirt, debris, algae, and other visible matter that could clog the filter, and you’re fine.

– Use an Algae Inhibitor

Liquid carbon is a popular algae inhibitor that’s also safe to fish and other aquatic creatures. This is also a common plant fertilizer, which means it works both ways. It will boost your plants’ growth and inhibit algae development at the same time.

Just make sure you get a reliable algae inhibitor and read the label before using it.

– Introduce Algae-Eating Aquarium Creatures

Many fish consume algae as a hobby, including guppies. Other fish species falling into the same category include bristlenose plecostomus, Siamese algae eater, otocinclus catfish, twig catfish, etc. Other aquarium inhabitants are even more effective at consuming algae, like nerite and apple snails and various species of tank shrimp.

These creatures will consume algae naturally, requiring a minimal investment from your part. The only downside would be that there’s a limit to how many algae eaters you can have. In many cases, you can’t have enough of them to inhibit algae growth enough without causing overcrowding problems.

It is, however, a reliable way of controlling algae growth with minimal efforts on your part.

Is Algae Bad for Guppies?

No, they’re not. I know this sounds like going against the purpose of the entire article, but look closely. Algae aren’t inherently bad for your aquarium since there’s nothing special about them. Algae are similar to plants. They rely on photosynthesis, they consume CO2 and produce O2 during the daytime.

Guppies even eat algae as part of their diet.

The problem arises when algae growth goes out of control, flooding the tank and suffocating the environment.

With that said, don’t become paranoid about having algae in your tank. They serve a good overarching purpose in the tank’s ecosystem. Just make sure you control the algae’s spread to prevent more extensive problems along the way.


There are multiple methods to control algae spread and keep the tank clean and thriving. Just make sure you perform regular water changes, clean the filter monthly, and have several proficient algae eaters in your tank and problem solved.

On a side note, use live plants in your aquarium. They inhibit algae growth, fish will occasionally eat them, and make the environment seem more lush and vivid.

Updated: December 9, 2021
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