Algae can be a frustrating battle at times; however, it's not a loss cause or a reason to completely strip a tank in most cases. Throughout this article, I will go over several types of algae, how to combat them, and how to correctly identify them. I will also address the cause of green water cause, typically thought to have been algae.

First off, most algae are caused by an overabundance of nutrients and light. Maybe your lights are too powerful, on too long, or too inconsistent. Perhaps you haven't thought about the window across the room that shines light onto the aquarium for 2 hours a day. There's a lot to consider when combating algae. However, finding the source is the first step to preventing and combating the growth, not getting fish to eat it! Although many fish may EAT ALGAE often by introducing them, this does not mean they will irradicate it. Instead, you may just be increasing the bio load and adding to the issue.

My point here is algae is caused by something, and it is managed by you and kept at bay by some fish.

Green Dust Algae (GDA)

GDA is your typical algae formed on the glass. It's slimy, green, or brown and easy to remove. Often it will also get on decorations, plants, and pretty much anything relatively smooth.

This algae is typically caused by too intense or too long a light duration. Therefore, controlling one or both may aid in mitigating its growth.

This alga is usually easy to clean; wiping or taking a sharp-edged object will remove it. Understand that this algae is very typical and often unavoidable to achieve things such as plant growth. A great cheap option to use is original magic erasers. (https://a.co/d/eHKsTLf) Ensure that it has no additives if you buy outside my link.

Now this is one of the easiest algae to combat with fish. Any algae-eating fish I list throughout this post will take to it, and although they will not irradiate it, they will control it to a degree. However, bristle nose plecos are one of the greatest for this type.

Green Spot Algae (GSA)

GSA appears very similar to GDA but is much thicker and harder to remove. GSA occurs over time and is nearly inevitable, like GDA.

Prolific GSA is due to high nutrients and intense lighting; however, similar to GDA, lowering light and lessening bio load will reduce the abundance of this algae.

GSA is harder to remove and will require a sharp-edged tool to remove. Furthermore, many algae-eating fish will not be able to remove it. However, they will pick at it.

First, you need to check the nutrient levels, especially phosphate, to get rid of GSA. If the levels are too low, adjust accordingly.

Once the phosphate levels are high enough, you can remove all of the algae with an algae scraper.

Also, make sure you don’t leave lights on for too long. Nine hours is usually enough for most fish tanks.

The best plan of attack when combating this algae is to remove it so it doesn’t build up consistently. This is especially important as the longer it sits, the harder it is to remove.

The best algae eater for GSA will be a small army of nerite snails. These guys tend to hover over one spot and eat away at it slowly.

GHA (Green Hair Algae)

Green hair algae is one of the most common algae issues aquarists combat. (myself included) It is also one of the most trial-and-error algae, meaning you may have to try several methods to correct the issue. Furthermore, you will notice no number of algae-eating fish will eliminate it. For example, I had to take out a handful of clump from my shrimp tank with 200+ and then put it in with 300+ BN plecos, which still exists in that tank after months. That being said, manual removal is the only way to eliminate it once it exists.

Let's talk prevention; light and nutrients play a considerable role like the other algae we have spoken of. However, this algae thrives in low-nutrient systems, typically with high light. You could ask yourself am I running my lights too long? Do I add fertilizer? Are my nitrates low?

This algae typically overgrows plants and fastly out competes them. Removal and adjustment are the proper way of addressing this. GHA will not disappear even if you adjust the problem. However, you will know your adjustments are working if it no longer grows.

If I had to recommend one aquatic creature to combat the issue, that would be Amano Shrimp; these are the only invertebrates I've noticed eating or picking at this type of algae.

BBA (Black Beard Algae)

BBA is the most treacherous algae to encounter. It is typically dark purple to black and grows primarily on decor (wood, decorations, rocks) or plants. It is nearly impossible to remove manually and spreads rather quickly.

The number one prevention to getting BBA is to avoid introducing it. Believe it or not, this is easier than it seems. It's as simple as treating all your plants before you introduce them. Dip them in hydrogen peroxide mixed with water for 5-15mins. Furthermore, the same can be done for plants or decor with BBA. As for dosing, I use the simple method that you know you've used enough hydrogen peroxide when the algae begins to bubble.

As for other factors to the growth and spread of BBA, high phosphate levels/high nutrients and light rapidly enable its ability to grow and thrive; prompt removal by treating it will prevent growth and spread. (DO NOT TRY TO MANUALLY REMOVE IT through picking at it WILL MAKE IT GET WORSE)

When it comes to fish/invert control, there're a few options. Amano shrimp and Siamese algae eaters will consume it if it's not too long. Otherwise, if you kill the algae via hydrogen peroxide or liquid carbon, these and many other fish/inverts will consume the dead algae. (BN plecos, OTOs, Shrimp, Chinese algae eaters, and more) Understand that if you kill BBA, it will turn white or brighter purple; however, if you do not have a fish or invert to consume it, it will likely sprout back up, killing the plants it's on.

Brown Algae/ Diatoms

Diatoms typically occur in new tanks. It appears as this small hair-like brown dust over the substrate or plants. This starts as a light brown dusting but can build to be a pretty thick ugly layer. Diatoms are plants, but they can exist with very little light. They are often associated with new tanks, high silicates, and high phosphate levels.

Diatoms are typically caused by the following

Insufficient lighting.
High levels of nitrates, silicates, or phosphorus and or low oxygen levels.
Immature fish tanks where the biological filter hasn’t completely matured.

Diatoms can be troubling to remove since there’re several methods to treat them; however, here are some options.

Deprive the algae of nutrients.
Use a vacuum to remove the algae from the substrate and wipe down the glass.
Perform water changes to extract nutrients.
Adjust lighting levels.
Ensure that your filtration system has a GPH rate of four or more significant.
Add more dissolved oxygen to the aquarium by adding an air stone or lowering the water temperature slightly.
Consider using RO water.
Blacking out the tank.

Fortunately, this can be combated with Oto’s and Plecos naturally.

Rhizoclonium Algae

This alga can be very misleading, often mistaken for hair algae. However, this algae is slimy, soft alga growing in fine brown or green hair-like strands rather like Hair algae. This algae is a form of green algae belonging to the Cladophoraceae genus.

I often obtain this in my shrimp breed-out tanks due to low flow from the sponge filters and water changing infrequently.

Therefore, you will typically get this algae from poor maintenance, low flow, and low nutrients. Fortunately, it is easy to remove, like hair algae. Just picking it out works.

There’s only one option for eradication, Amano shrimp.

Blue-Green Algae or BGA (cyanobacteria)

This is when we get into the 'not technical algae, algae.' Blue-green algae is a bacteria rather than an algae. It grows in thin layers that, as they get thicker, can be removed in slimy, smelly sheets. The most common variety in freshwater is a vivid green, but it can also be reddish or brown. It is incredibly suffocating and spreads rapidly.

Being a photosynthetic bacteria/algae, it typically appears present when the lights are on and almost dies out when the light goes out.

BGA is typically acquired via introduction to the tank. You usually receive a plant or decoration that has this bacteria on it.

Again the best action to prevent this is dipping plants and decorations in hydrogen peroxide.

No fish or invert will consume this; if fish or inverts try to consume it, they can get sick and die from the bacteria.

Fortunately, there're a few ways to eliminate it and eradicate it.

Green-blue algae remover. This product is power based and will eliminate it. However, it does reduce oxygen levels in the tank and causes fish to suffer. (This is the best method to eradication)
Blackout is another option. However, it needs to be extremely thorough. NO LIGHT can enter the tank. Therefore, the best practice is to wrap the tank in trash bags to stop any light from entering and turn off all the lights.
Lastly, the increase in flow will strip it from the blanketing state and allow it to get into the water column for treatment and get filtered out.

The best practice is to use all 3 of these methods in conjunction to eradicate it. Removing this is essential at first sight as it will kill fish and plants quickly.

Green Water (Free floating Algae)

Green water is commonly considered algae; however, nothing will happen if treated with algae removers. Green water is hard to remove but simple if done right.

Green water is typically caused by lights being on longer than necessary and or direct sunlight from outside. The more prolonged and more intense the light, the more likely and quicker the water will turn green.

I firmly believe that there are only two methods to eradicate this.

UV sterilizer. I believe this is the only proper and safe way to eradicate green water. Depending on the severity of the green water, it may take between 3-7 days to clear up.
Heavy water changes. You nearly need to remove 75% of the water daily while reducing light to the tank. In my experience, this is still no guarantee to eliminating green water. Being its bacteria, it only takes a little to remultiply. Furthermore, these heavy water changes can be highly stressful to fish within the tank.

Green water isn’t deadly; rather, unsightful. I firmly believe that obtaining a UV sterilizer is the only way to eliminate it.

Dealing with Algae in Freshwater Aquarium

Homebred Aquatics

Dealing with Algae in Freshwater Aquarium

Substrates

Homebred Aquatics