Green Aquarium Water – Causes and Cures

Green aquarium water
Care & Maintenance

How to Get Rid of Green Aquarium Water

Aquarium care can be tricky. You think you know what you are doing, then one day, you can see changes in the watercolor. Fortunately, many aquariums experience green algae in their water. Green water can be an unpleasant sight. Often times, pet stores have to transfer fish from tank to tank to ensure the water column is being properly taken care of.

Keep reading this guide to discover the appropriate solution for your aquarium and tips to prevent another green water experience.

dirt in fish tank water

What Is Green Aquarium Water?

Green aquarium water happens when there is an accumulation of green algae called phytoplankton. These tiny organisms are so small that they are not visible to the naked eye. Some people think they can see something moving in the water if they look super close. They just discolor the water and make the tank look like you filled it with pea soup.

When you first see the algae build up in the tank water, it is a dark green color. Others say the color resembles a lime. Though this appears normal, over time, the phytoplankton causes the water to cloud up and can get so bad that you cannot even view your fish. Algae can grow on the surfaces of your tank, which makes everything difficult to view.

Fortunately, the phytoplankton algae are not threatening to your fish or any life in the aquarium. All it does is make the water turn green. The algae provide some of the same nutrients that aquatic plants provide for your fish. Algae thrive off of high oxygen levels and nutrient-dense fish food.

Though it does not harm the lives of your aquatic creatures, green water is not pleasing to the eye. Plus, you cannot even see your beautiful fish swimming around. Of course, the overall goal should be to maintain clear water so that you can enjoy your fish tank.

What Are the Causes of Green Water?

To properly get rid of the algae growth in your aquarium, you should understand the causes of green water. There are a number of factors that contribute to the development of your green water problem. Understanding them can help you treat the problem and prevent the algae from returning to its previous conditions. Here are some of the top reasons for green aquarium water.

An Imbalance of Nutrients

The green algae need nutrients to grow. Therefore, if you add nutrients to the aquarium, then you need to make sure that you put in the proper amount. Too much of one can create a green mess.

The two primary nutrients to watch out for are nitrates and phosphates. It is a fact that phytoplankton treat these as their food source. If there is an imbalance of nitrate or phosphate levels, then the water can turn to a green underwater environment. Nitrates and phosphates typically come from fish food or fish waste. In a number of other cases, tap water was the perpetrator.

You should access the size of your aquarium. Every fish container holds a different volume of water, which is usually measured by the gallon.

Too Much Light

Light is also one of the potential causes of green water in your aquarium. When in the presence of light and nutrients- like nitrates and phosphates- the green algae grows like crazy through the process of photosynthesis. Plant cells thrive in conditions where photosynthesis is repetitive. Lighting problems can stem from a high amount of direct sunlight. A tank light with a lot of power can add to the green water situation. No matter the light source, it is always best to maintain low levels of light exposure.

Wherever you place your aquarium, be sure that there is plenty of room to move your fish in and out of direct sunlight, without causing a hassle.

Overall Poor Maintenance Habits

aquarium algae

Owning an aquarium with fish comes with many responsibilities. Without proper aquarium maintenance, your fish’s health and the water quality are at risk. Not following a cleaning routine can form unpleasant algae blooms.

All aquarium owners should make it a hobby to perform regular water changes, filter cleanings, water quality checks, gravel cleanings, and removal of uneaten fish food. Doing all these steps can ensure that you maintain a healthy fish tank. In many cases, aquariums may purchase or use an algae eater to help keep up with the process of waste maintenance.

How to Get Rid of Green Water

There are multiple remedies to remove the free-floating algae from your fish tank. If you think you know the reason behind the algae growth in your tank, then choose the cure and take the steps that best relate to your condition. Overall, here are some ideas to get your clean water back in order in your saltwater or freshwater tank.

UV Filter

UV filters or UV sterilizers are types of equipment that can dissolve the free-floating algae cells. The result is clear water within a few days. Using this product is one of the easiest ways to remove pesky phytoplankton from your water and container surfaces. All you have to do is turn it on.

When you use a UV sterilizer, the water flows through a UV chamber site where algae and bacteria are exposed to ultra-violate light. There, the algae are eliminated. The best part is, the sterilizer has no negative effects on the aquarium habitat, nor the fish species, plants, or invertebrates living in your tank.

If a UV sterilizer is the best option for your aquarium, then there are many variations to choose from. No matter the tank size, you can quickly eliminate water discoloring algae and bacteria with the use of a UV light.

Filter Pads

The filtration system in your aquarium cannot trap the algae that cause green water because it is so small. Water pads can change this for the better.

Adding one of these things to your filter can trap the algae that would typically slip through the filtration system. However, the pads clog easily. You should always have multiple on-hand so that you can change them quickly, preventing any type of nutrient build-up.

Eliminate Lighting

As mentioned before, algae feed on excess light and oxygen. For this, one of the greatest ways to rid the aquarium of green water is to remove the light for a certain period. Covering the tank with a blanket or taking it out of sunlight can work to prevent algae bloom and growth. It can also cause it to die off.

You should also pay attention to the intensity of the aquarium lighting. Free-floating algae thrive when there are bright aquarium lights hard at work. If your light source seems to be on the intense side, then you may want to consider dimming it down or getting a different color.

Removing the light source is not a foolproof way of clearing your green water, though. If, after two to three days of coverage and there is no improvement, then there is another cause for algae growth. A different course of action is a recommendation.

Diatom Filter

Expert fishkeepers and tank owners know that having this device is expensive and out-of-date. However, they use diatomaceous earth to collect small particles that float through the water.

Diatom filters have developed over time, despite being considered obsolete. Simply, there are just better ways to remove green aquarium water. Today, these filters can be adjusted to fit with regular water filter media cures.

Adding Chemicals

For direct results, utilizing a chemical treatment works quickly. However, it is not the most efficient method of preventing the issue. Treat this as a last resort, especially if it involves ammonia. The effect of anything with a chemical extent should not substitute proper tank preservation.

Every tank’s water chemistry is different. Aquarists have different numbers of fish, unique aquarium plants, and they may or may not have a substrate. In addition, while the chemicals are effective in removing algae bloom, you do not know how they affect the chemical or ph balance of your fish tank. Balancing the chemical levels in a freshwater tank takes time and can cause an abundance of issues on a large spectrum.

The chances are that you are not going to kill your aquarium fish by putting in too much chemical treatment. Keep in mind, though, for sure what problems could arise from a combination of improper amounts. Do your research to ensure a proper chemical to gallon ratio.

How to Prevent Green Water from Returning

You now know some cures that may solve the problem, but what happens if it all returns? It would be a waste of time to start from square one all over again. You need to know prevention methods to keep green aquarium water from returning. Here is some information on making an effort to uphold a tank preservation system that protects it from unwanted algae inhabitants.

Installing Proper Lights and Controlling Sunlight Exposure

Controlling light exposure in fish tanks is a fantastic step to preventing green aquarium water. Any form of light affects the green water problem, including sun-light. A lot of participants make the mistake of putting their tank next to a glass window. Overall, more light means that there is a higher possibility of an abundance of algae.

To prevent unwanted blooms of algae, consider different sites for your tank, maybe a place that does not come into direct contact with sunlight. If the tank does contact daylight, then an easy fix is to draw the curtains when you are away to give the fish a rest.

Overall, a water tank without plants requires less than six hours of sunlight or light energy. Tanks with live plants need about eight to 12 hours daily.

Introduce Live Plants

Adding plants to your aquarium is another way to reduce the likelihood of concentrations of green water. Plants require similar nutrients as algae for sources of food and energy for growth including oxygen.

Hornwort is a plant that, when properly grown, can reduce the algae problem in aquariums like magic. Duckweed is another example plant for a bit of algae control and prevention.

Pay Attention to the Proper Dose

If you dose your aquarium with liquid plant fertilizers, you should always be careful with the amount you put in the tank. If you do not know the proper amount for your tank size, then the best thing is to aim for a smaller quantity. Excess chemical concentration can cause green water, especially if you do not have live plants or a couple of sources of CO2.

Regular Water Changes

Everyone from fish keeping beginners to absolute experts should understand the importance of regular water changes. Doing 10 percent every week or 25 percent every two weeks not only prevents a bloom of algae but also keeps your aquarium healthy. Problems can arise when you neglect water changes or don’t ask for advice with common questions. You could see a difference in fish health, or the watercolor could completely change.

Appropriate Food Levels

overfeeding fish

Feeding your fish too much food can be a nothing but a disaster case. First, your goldfish is probably not going to eat all the food you provide. When it sits in the tank, the food releases products that the algae feed on, such as phosphates and nitrates. If you control the amount of food you put in, then you do not have to worry so much about your goldfish suffering from green water.

Releasing Daphnia

Another idea to prevent green water is to release daphnia into the aquarium. Daphnia is a species of water fleas that can control the algae by eating it away. These small algae eaters are also a treat for many fish. Be sure to identify the cause of your green water, though. These little critters only impact aquarium water with phytoplankton. No one should be afraid to update their aquarium. Green water can continue to culture on the walls of your container.

Regularly Test Water

You should regularly test your aquarium water for certain minerals and solutions. Nitrate and phosphate are commonly found in tap water, which helps contribute to an algae bloom.

Other Critical Maintenance Habits and Thoughts

A simple water change is not enough to keep your aquarium clean and beautiful. You should also clean out uneaten fish food material, fish waste, and any rocks, gravel, or decorations at the bottom. Also, check for nitrate and phosphate units in the aquarium.

Not keeping up with aquarium maintenance can lead to the possibility of green consequences.


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