A little bit of algae is a normal part of any aquatic ecosystem and can even be good for your fish. But when it gets out of control, you have a problem on your hands.

Algae can raise the pH of the water too high for fish, starve the tank of oxygen at night when aquarium lights are off, block filters and bother your inhabitants.

In this guide, we’ll look at what you can do to get rid of the most common types of aquarium algae – and how to keep your tank in perfect harmony to stop algae from growing in the first place.

Algae growth (and control) all comes down to the light and nutrient levels in your aquarium.

The right balance of light and nutrients (phosphates, nitrates, and silicates in particular) will perfectly support the plants, fish, and other inhabitants in your tank. But if anything is a little out of whack, algae can move in.

• Too much light in the aquarium

• Overfeeding fish

• Too much plant fertilizer

• Too little plant fertilizer

• A brand-new tank

• New plants

• Old plants with old growth

• Minerals in your water (e.g. if your tank is filled with tap water)

Finding the right balance for your tank to keep algae levels in check is a challenge, especially as there are so many types of algae, not to mention the endless number of aquarium setups.

But with a little understanding of how algae work, it’s totally possible to find the right solutions for your tank.

There are plenty of methods you can try to reduce and prevent algae. Take a look at these suggestions and consider what may work for your style of aquarium.

However, make sure you don’t make too many drastic changes at once. Just try one solution at a time and wait a couple of weeks to see how it affects your tank.

Cut down how many hours your aquarium’s light is switched on. If you have a lot of plants, try cutting it down to just eight hours a day. If you have no plants at all (or only have low-light plants such as mosses), turn it off entirely, at least for a few days.

In extreme cases, some aquarium owners do a ‘blackout’. This means completely covering the whole tank with black sheets to keep light out entirely for a week or so.

Algae need light to thrive – so starving it from this resource is an easy and effective way to tackle it.

Plants outcompete algae. In other words, they eat up all the nutrients that algae like, leaving nothing left for them. This makes plants some of the most effective, long-term soldiers against algal growth.

Fast-growing plants are able to tackle algae levels pretty quickly – though they require more maintenance in the long run. A good balance may be a combination of fast- and slow-growing species.

Unhealthy plants attract algae, but those in good shape will help prevent it. Trim dead leaves, prune plants into shape, and give them the right level of fertilization and plant food.

If you’re a beginner or short on time, choosing ‘easy’ plants that don’t require much maintenance will be a helping hand here.

Many aquarium keepers swear by algae-eating species, which chomp up many common types of algae. Depending on the biome of your tank, you could make friends with:

• Catfish, such as otocinclus, corydora and nerite for larger tanks

• Snails, such as ramshorn

• Amano and Cherry Shrimp

• Siamese algae eaters

Regular maintenance and cleaning will already be a cornerstone of your aquarium care, but some tasks are especially important for tackling algae.

You can manually remove algae by scooping it out, using a pad or scraper, wiping down plants, and scrubbing the sides of the tank. Another vital task is keeping your substrate clean, by siphoning up the debris and waste.

Use test kits to keep on top of the nutrient levels in your tank. This will help you see whether you’re dealing with too much (or too little) of particular nutrients in the water – and can take steps to adjust it accordingly.

A high-quality filter can make a huge difference when it comes to removing algae and its spores. Try increasing the capacity of your filter, or replacing it with a more powerful one – such as Oase’s BioMaster.

Check the water circulation too the better the water can circulate, the better it can be filtered. Add an air stone, powerhead, or bubbling feature to get it moving.

Different types of algae need different battle plans. Let’s take a look at some of the most common algae species found in aquariums, and what you can do to fight them.

Brown diatom algae appear as brown patches on your plants, and as a dusty-looking, flour-like substance on the walls and surface of the tank.

It’s very common in new tanks. Usually, it’s caused by excess nutrients, especially phosphates and silicates.

And the good news is that it’s easy to tackle. Algae-eaters of all kinds love brown diatom, and as your plants grow, they’ll also scoop up all the nutrients in the water –starving the algae. You can also remove brown diatom manually, by gently scrubbing with a brush or using an algae scraper.

You can tell GSA, or green spot algae, by the little green circular dots it forms on your plants, tank walls, and surfaces. It’s very difficult to dislodge.

If this is the only type of algae in your tank, it may actually indicate that your plants need more nutrients, particularly phosphates. So, a great way to tackle it is by supporting your plants’ growth: use a phosphate fertilizer, add a CO2 injection, and prune away any dead leaves.

Nerite snails also love GSA - so think about increasing your snail population too!

As the name suggests, green dust algae have a very dusty texture. It’s usually found as a thin green film on the aquarium walls and is very common in new tanks.

GDA is a bit of a tough one to tackle – not because it’s persistent, but because it can be caused by any number of things. A few good tactics you can try include:

• Adding lots of plants but keep them trimmed and remove dead or affected leaves

• Changing the water frequently, especially for a new aquarium

• Keeping light levels low

• Monitoring CO2 levels in the water

• Lowering the water temperature

Black beard algae is exactly what it sounds like: algae that forms in little black hairy tufts in your tank.

Annoyingly, BBA can take a while to get rid of. There aren’t many algae eaters who like it either – though you may have some luck with siamese algae eaters and flagfish.

Otherwise, the best thing to do is to just keep on top of your general aquarium maintenance. Siphon away the detritus on the substrate, trim your plants, and stabilize the CO2 levels.