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Saltwater Algae: Benefits, Effects & How to Manage (With Pictures)

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By Lindsey Stanton


Cultivating algae probably isn’t the first thing that comes to mind when you think about these chlorophyll-containing organisms. After all, they’re not true plants. Yet they’re green and use photosynthesis to produce energy. While they can be harmful, many species are beneficial for saltwater tank communities1.

Noxious algae can occur in aquariums for several reasons: an overabundance of nitrates, sunlight or UV light exposure, and poor maintenance. This scenario produces conditions with plenty of things for algae to eat, which eventually leads to an algal bloom. This, in turn, will deplete the dissolved oxygen. That’s the bad side of algae.

To understand the pros of adding algae to your tanks, it’s essential to look at its role in the ocean’s food web. It exist in both freshwater and saltwater. These microscopic algae species are a vital food source for many marine animals, including filter feeders, crustaceans, and invertebrates.aquarium plant divider

Benefits of Saltwater Algae

The primary benefit of saltwater algae for your tank is that it can provide reliable food for many of the species that you may have in your aquarium, such as blennies, surgeonfish, and tangs. That’s a significant contribution to the health of your tank because it limits the other foodstuffs that you may add to your tank, which can have adverse effects on the water quality.

Algae can also help control nitrite and nitrate concentrations in your tank. High levels can create a toxic environment that few species can survive. That said, it’s worth noting that these compounds can cause harmful algal blooms that can lead to these unhealthy conditions.

A saltwater tank is often not just a place for fish to swim, but it’s also a living macro-environment. That’s part of what makes it so rewarding. Algae can add a welcome aesthetic to your aquarium that will bring a bit of the ocean into your home. After all, there’s a good reason that nearly 2 million American households have a saltwater tank2.

Image Credit: Damsea, Shutterstock

Types of Beneficial Algae

Of course, not all algae species are favorable additions to your tank. Many of them fall under the broad category of microalgae in reference to their microscopic size. These are the ones responsible for fish kills, with the potential to even be harmful to humans. However, there are many algae species that you should consider adding to your tank because of the advantages they offer.

Many macroalgae offer excellent food sources for your marine community. Many also do double-duty, improving the water quality and keeping excess organic compounds in check.

Species to consider include:
  • Prickly Sargassum
  • Lettuce algae
  • Neptune’s Shaving Brush
  • Cactus Algae
  • Feathery Caulerpa
  • Limu Manauea

Algae are the favored food of many fish and invertebrates. You can match the algae species with the fish in your tank, as there are numerous varieties available. Other algae act more as decorative additions, such as Smooth Leaf Kelp.

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What You Can Expect With Saltwater Algae

Adding saltwater algae to your tank brings a new dynamic. It can affect how much you feed your fish, as well as the water quality, in several ways. Algae will have similar effects on water chemistry because they conduct photosynthesis. That process uses up carbon dioxide and releases oxygen in the tank.

Some algae species have particular requirements to thrive, from lighting to nitrite levels and nutrient concentrations. Some may fare better in a refugium instead of your aquarium. We recommend researching any that you are considering to make sure they’re a good fit for your marine community.

Managing Your Saltwater Aquarium

The water chemistry is the top priority for saltwater algae. You’ll likely see a range of parameters involving pH, nitrite, and nitrate levels. Some species, such as the Halimeda Algae, need supplemental calcium. The other part of routine maintenance is pruning. Some algae are fine, but an overgrowth can cause problems. Species vary in their tolerance to this practice.

A less-invasive alternative is to add a few algae-eating fish to your tank to do the work for you. Animals such as the Margarita Snail or Chestnut Cowry are voracious eaters. Other candidates include Sea Cucumbers and Starfish. You can try other measures, such as adjusting the water flow or lighting to get things under control. Using Aragonite as a substrate can reduce the nutrient load of your tank.

Bear in mind that some of these creatures may perish if there are not enough algae to go around for them. That makes balance a critical factor if you decide to go this route.

If you're new to the world of goldfish or are an experienced goldfish keeper that loves to learn more, we recommend you check out our best-selling book, The Truth About Goldfish, on Amazon.

From diagnosing illnesses and providing correct treatments to ensuring your goldies are happy with their setup and your maintenance, this book brings our blog to life in color and will help you to be the best goldfishkeeper you can be. 

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Summing Up

Introducing saltwater algae to your tank can take your experience with marine tanks to the next level. It brings more challenges but has a slew of benefits that can create a healthier environment. Remember that your aquarium has limited space for what it can support. However, you may find that carefully chosen algae species can make it the proverbial win-win.

Featured Image Credit: Damsea, Shutterstock

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