How to eliminate Green algae


After reading our Blog discussing ways to identify different types of algae we are now going to go through the types of algae and ways to combat these and eliminate them from your tank. Let’s firstly discuss the Green algae.


Green algae are a very common occurring algae in any freshwater aquarium. These appear due to several reason and correcting these can help solve the issue.

Green Spot Algae

Green spot algae are small round spots that appear on solid surfaces. The most common place you will see this is your glass, but it can also grow on slow growing plants or even decorations on your aquarium. This kind of algae normally appears due to low phosphate/Co2 levels. With this type of algae there isn’t a aquarium inhabitant that will take this stuff down for you. Some snails like nerite snails can do a bit of cleaning but won’t do it well enough to consume the algae before more grows. These algae isn’t too difficult to remove, just take an algae scraper and scrape it off.


To address the issue of this algae its best to try adding some phosphate to your tank which should help to stop the growth of this. Be careful not to add too much though as this can cause other algae to grow. The recommended amount of phosphate in an aquarium is 0.1 to 1 mg/l of phosphate (PO4). This is a nutrient used by plants so be sure to always keep an eye on it to ensure it stays relatively stable. Most all in one fertilizers have phosphate in it, Like Tropica Premium and Tropica Specialised Aquascaper Complete plant food.

Green Dust Algae

A similar looking algae to the green spot algae, green dust algae is more common in high tech setups. It gets its name due to its green dust-like appearance. This algae usually forms on glass or hardscapes/decorations. Unlike Green spot algae, Dust algae doesn’t go away after scraping it off the surfaces. This is because the algae is actually small individual cells that are capable of movement meaning if you scrape it off, it will move to another spot or return to the same spot and carry on growing.


Its main cause is Low Co2 and Low nutrients within your aquarium. The best way to get rid of these algae is to wait for it to grow out without being disturbed. Once it forms a thick green layer it can be removed with a syphon to suck the algae out of the tank inn larger chunks. To prevent it from returning you will need to address the low nutrient issue. Increasing the amount of fertilizer, you use should assist with this. Slowly increase the amount you put in until these algae stop appearing.

Green Fuzz Algae

Green fuzz algae like most thread algae usually indicate low or fluctuating CO2. This type of algae grows threads of a couple of millimetres on plant leaves. It shows that the plants are suffering due to a nutrient issue. You can get algae eaters like amano shrimp which will keep these algae away.


Like all algae problems, the main issue needs to be addressed to prevent it from growing. You will need to make sure that you are using correct amounts of Co2 and that it is being injected according to the lighting period. We discuss how to set up Co2 in our high-tech planted tank guide. Other supplements are available such as Seachem Excel and Easy-Life EasyCarbo which are a source of carbon for low-tech tanks.

Green Beard Algae

This is another Thread type of algae that again can be caused by low or fluctuating Co2. When it comes to green beard algae, it likes to attach itself to plants and hardscape and can grow a few centimetres creating a green coat on the surface. Algae eaters love this stuff so purchasing the correct algae eaters for the job will help clear it up fast as manual removal of this can be difficult due to how well it attaches itself to surfaces.


Addressing the issue for this algae is important to ensure it doesn’t come back if you do not want it to. Reducing lighting in your tank can help to remove the algae. Adding plants if you do not already have them can help with this also. If you do not want plants in the tank try some floating plants on the surface. In the planted tank it can mean that your Co2 is incorrect or that a nutrient is missing usually nitrates. Try increasing these to address the issue.

Green Hair Algae

This is a strange wool like algae which have long threads usually a couple of centimetres long. These do not stick to surfaces and usually appears on tanks that have low nutrient levels. Co2 and flow can also be a part of the issue so you need to make sure these issues are address to eliminate this algae from the tank. Algae eaters also love this stuff to be sure to stock a good couple of these in your tank to keep it away.


If you see any, be sure to manually remove this, using a syphon is usually the preferred method as it prevents any of it from getting lose when pulling it up from the gravel.

Green water

This is a floating algae which is usually made up of lots of organisms, It can be very difficult to eliminate but implementing the correct steps can help to remove it from your tank. It is normally caused by an imbalance in the tank and is pretty much always caused by a water quality issue. A commonly used method to remove this type of algae is to do a blackout on the tank meaning no light gets in at all for 4 days. Be careful though as the dying algae can cause ammonia to rise. Always make sure that during a blackout the tank gets enough aeration too or you can lose your fish to this. Another way to address the issue is to use a UV steriliser. This helps by killing the algae in the water when it is passed through the UV unit.