Freshwater Algae                  
  Article by Bubbles Aquarium                    
  Photos taken by Michael G.W. Wong                  
  Where there is water, light and nutrients there is algae. In an aquarium, algae may come from many places, through algae spores in the air or in the tap water. They can be introduced into an aquarium as small filaments attached to plants or even in the digestive tract of fishes. Not all algae in the aquarium is necessarily "bad", a certain amount is inevitable. Good algae is usually present in small quantities and indicates good water quality and is easily kept in check by algae eating fish or simple removal during routine maintenance. Bad algae on the otherhand is either an indication of bad water quality or is a type of algae that tends to overtake the tank and oftentimes very difficult to eradicate.  
  Algae has several undesirable effects in aquariums which have probably prompted you to go to great lengths to achieve its successful control and treatment. The most obvious effect of algae is the visual degradation of the appearance of your aquarium. The goal is to create an appealing environment with a high degree of clarity. Algae growth on glass, rocks, driftwood, plants, equipment etc. challenges the achievement of that goal. Less obvious, but more severe effects of algae is its negative impact on plants and fish life. Excessive algae growth or algae blooms will crowd the water environment in your aquarium and severely threaten plant life by competing for nutrients and blocking off their light source.  
  Beginners as well as experienced hobbyists have, at one point or another, all had to deal with the undesirable effects of algae. The best approach in my opinion is to be able to recognize the different types of algae that you may encounter... "Knowing your enemy is half the battle". In this article we will focus on the most common types of freshwater algae and try to understand their cause as well as potential treatments and prevention.  
  All pictures on this page are copyrighted. Please do not copy without permission.    
  Blue Green Algae  
  Sometimes referred to as slime or smear algae. This is actually an organism cyanobacteria which requires nitrogen, CO2 and a light source to live. There are many types of BGA and may come in many different colors. It forms thin slimy sheets and can spread rapidly throughout the entire aquarium. Sometimes giving off a swampy or musty odor. If left unchecked it can kill plants by smothering them and cutting off their access to light and oxygen. BGA can produce its own nitrogen, so depriving it of macro nutrients (N, P or K) through water changes usually has no effect on controlling it. Blue green algae can appear out of nowhere and even breakout in well maintained mature tanks. Early signs of BGA can been seen in small quantities on the aquarium glass below the top layer of the substrate (particularly in the front and side glass). BGA can be removed mechanically but is not a viable solution as it will return quickly.   
For extreme cases treatment with 200mg of erythromycin phosphate for every 10 gallons of water (40 Liters) is very effective and will usually eliminate BGA within a few days. If BGA can still be observed after 4-5 days then repeat the treatment. Charcoal filtration and UV equipment must be turned off before applying treatment. This type of treatment may have some effect on the biological filter so be sure to track ammonia and nitrite levels. To prevent the development of antibiotic resistance, do continue the treatment for several dosages after the slime is all gone. If not, it may come back again within a few months and the antibiotic may not work again or work as well.  
  Day 1       Day 2             Day 5        
  Applied erythromycin phosphate Top layer BGA disappeared         Substrate free of BGA      
  As we mentioned earlier, BGA in a planted tank usually forms between the substrate near the front of the glass where there is a source of light. When you first see it you probably dont pay too much attention to it because it looks harmless. But after awhile you start seeing more and more, and eventually, some of it has started to creep up and onto the top of the soil (see top left photo). Once in the open with full access to lighting, CO2, and nutrients, BGA can spread quite fast. You try removing as much of it as you can manually but it seems to come back just as fast.  
  If you're having BGA problems, for starters try adding some SAE's and Abalone Snails to your tank. They can actually help slowdown BGA and keep it in check. Many people have said no algae eaters will eat BGA because of its toxicity but we have seen these two algae eaters in action and they do quite a good job against BGA. The Abalone snail is very useful and good at getting to the source. It can make its way down the aquarium glass eating up the BGA (see before and after photos below). They dont seem to go too far down the substrate, sometimes maybe 2-3 inches at most. They are excellent helpers to have around but will not rid your tank of BGA. However, it consumes enough to slow down the BGA from reaching the top layer of the soil. Ocassional the Abalone snail will stir up some BGA to the top layer of the soil, this will be quickly eaten by SAE's. "Lazy" SAE's on the other hand will not eat this because they are probably just waiting for some tasty fish food.  
  Before                    After            
  SAE's hard at work                    
  Green Water  
  Early stages of Green Water         Full algae bloom        
  A true unicellular algae known as green water but sometimes referred to as "algae bloom". This type of algae floats in the water column and can reproduce rapidly and take over an aquarium in a matter of days. During the early stages of green water the tank will appear cloudy (whitish color), sometimes mistaken for a "bacterial bloom". If left unchecked, the algae will continue to bloom and eventually turn the entire water green. The situation that causes green water in the first place is usually a combination of high nitrates, phosphates, and excessive lighting (in particular direct sunlight). Situations where there is no direct sunlight to come in contact with the aquarium then substrate disturbance is usually the culprit of algae blooms. Massive water changes will only temporarily improve the clarity of the water but will not rid a tank of green water. Although very unpleasant looking green water is not harmful to fish.   
  There are several methods for eliminating green water. For immediate impact, try UV sterilizers which prevents the algae bloom in the first place. UV Sterilizers will kill free floating algae, parasites and bacteria making your water sparkling clear again. Probably the best solution for green water problems, however, UV sterilizers will also oxidize trace elements in the water and render them unusable to plants.  
  7th day into the algae bloom               3 days after installing UV sterilizer    
  Other methods you can consider trying if you're having green water problems...        
  (1) "Blackout" method - Covering the aquarium completely so that no light whatsoever gets into the tank. Be sure you turn off your CO2 and add an airstone if possible. Keeping the aquarium covered between 3-5 days will usually eliminate the algae bloom. After the "blackout" period do a 40% water change, replenish plant nutrients, and resume lighting and CO2 as you would normally. Personally, we have not tried this method before and do not know the impact it will have on some of the higher demanding plants. If you dont have any plants in your tank then this method should be the least expensive and most effective way of eliminating green water.  
  (2) Another method you can try is adding micron filter cartridges or diatom filters. These can quickly remove the algae from the water column and prevent it from decaying in the tank.  
  (3) If live daphnia is available try introducing a large number of them into your green water tank. These will eat the free floating algae cells, and will, in turn be eaten by the fish. However, if your fish stock is high then this method is probably not the best choice for you.  
  (4) Barley straw extract. Just add some into your filter and it will help remove your green water problems.  
  (5) Your last alternative to your green water problems is chemical algaecides/flocculents. Not really recommended since they will cause harm to fish and invertebrates especially if the incorrect dosage is used.  
  Green Spot Algae                    
  These are hard, round, green algae spots that usually form on the glass and on leaves of slower growing plants. This type of algae is considered normal for high lighting planted tanks. They do not often become a serious problem but if left unchecked they can reproduce and spread rapidly. In large numbers they become unsightly and may ruin the overall appearance of an aquarium you are trying to achieve. Must be removed mechanically... Razor blades are very effective but they have a tendency to oxidize and is not very safe to have around if you have children. We recommend KENT Pro-Scraper, it's rust resistant, safer to use and to have around, and will easily remove green spots from the glass. A quick scrape of the glass followed by a water change is all that is required to keep this algae in check. In more serious cases, remove affected leaves and/or plants. Bleaching equipment such as heaters, CO2 diffusers and filter tubing may be required. It also helps to have some Neritina snails, Plecostomus sp "dwarf", Plecostomus sp "gold" or Whiptail catfish around to help consume some of the green spots.    
  Black Spot Algae                    
  These are very tiny black algae spots that have a course texture to it. They usually grow at the base of plants, then make its way up the stem affecting older leaves. They will also grow on driftwood, rocks and equipment. This type of algae is considered a "bad" algae. It is very difficult to remove manually and if left unchecked they can spread rapidly throughout the tank.  
  If you're having black spot algae problems try adding some snails into your tank, in particular, (from left to right) Neritina Ruby, Neritina Spiky, Neritina Zebra. These snails will help keep black spot algae in check and keep your driftwood and rocks looking algae free (see pictures below). It seems Amano shrimps like to eat this type of algae as well.  
  Before     Neritina Zebra Snail Amano Shrimp    Five Days Later    
  Brown Algae                      
  Brown algae are actually diatoms. They form thin brown patches and can settle on most surfaces, usually on plants but are most visible on the glass of your aquarium. This type of algae is quite common in low lighting setups especially during the early stages of an aquarium's life. The situation that causes brown algae to appear is usually a combination of high levels of silicate and phosphate. It is fairly easy to deal with, it can be easily brushed or scraped off manually. Otocinclus affinis are excellent little fish that will clear every surface of this algae and keep it in check. Increasing the lighting on your tank will also make the brown algae disappear.  
  Green Hair Algae                    
  This type of algae is extremely fast growing. Consider a "bad" algae that usually grows on plant leaves and weaves its way in and around creating thick matted clumps. It is bright green in color and has a very fine slimy texture. Individual strands can grow as long as 20 cm. Cannot be removed easily mechanically. If left unchecked it will spread and overtake an aquarium under good water conditions. The situation that causes green hair algae to bloom is usually a combination of excessive lighting, high levels of dissolved organics and/or nutrient imbalance, in particular, excessive iron.  
  If you're having green hair algae problems try removing as much algae as possible with a tooth brush or with your fingers. Then add some SAE's and Amano Shrimps to your tank. These algae eaters will quickly control and eventually eliminate this type of algae from your tank. Smaller types of shrimps also eat this algae but not as effective as Amano's and SAE's.  
  Black Hair Algae                    
  Another extremely fast growing type of algae. Normally black in color but sometimes may appear slightly grayish. Individual strands can grow as long as 5 cm and have a more coarser texture than green hair algae. It is very difficult to remove manually and is considered a "bad" algae. This is probably one of the first types of algae you need to battle with. Will usually appear in newly setup planted tanks attaching itself on edges of plant leaves, substrate, and equipment. If left unchecked it can spread very fast and sometimes smother and kill plants. Cutting away affected leaves is one option but will usually not rid your tank of black hair algae. The most effective algae eater that can keep this algae in check is the Amano Shrimp. In severe infestation you will need to manually remove affected leaves and/or plants. Smaller types of shrimps also eat this algae but not as effective as Amano shrimps.  
  Brown Hair Algae                    
  This type of algae is very similar to green hair algae. Also consider a "bad" algae. They both have the same fine slimy texture. The only difference is that brown hair algae thrives under very low lighting conditions. Individual strands can also grow as long as 20 cm and usually form matted clumps in between plants and on the substrate. If left unchecked it will spread and overtake an aquarium under good water conditions.   
  If you're having brown hair algae problems try removing as much algae as possible. Then add some SAE's and Amano Shrimps to your tank. These algae eaters will help control and eventually eliminate this type of algae from your tank. Smaller types of shrimps also eat this algae but not as effective as Amano's and SAE's.  
  Green Dust Algae                    
  This is that dusty looking green algae that coats the front and side glass. Considered normal in planted tanks and generally a good sign if that’s the only algae that is noticeable in your tank. A quick scraping of the glass prior to your water change is all that's needed to control this non nuisance algae.  
  Fuzz algae                      
  Grows mostly on plant leaves and on the aquarium glass. Individual strands only grow about 2-3mm long and is green in color. Consider normal for high lighting planted tanks. Not particularly fast growing and can be easily scraped off the glass. Smaller shrimps such as crystal red, red cherry, bee, tiger and blue shrimps can help keep this algae in check.  
  Staghorn Algae                    
  Looks very similar to black hair algae when there is a lot of it concentrated in one area. But in a close up view, staghorn is grayish in color, much thicker and has a courser texture, and branches profusely like "deer antlers". Individual strands can grow as long as 5 cm. It is very difficult to remove manually and is considered a very "bad" algae. If left unchecked it can spread very fast attaching itself any surface. Cutting away affected leaves is one option but will usually not rid your tank of staghorn algae. The most effective algae eater that can keep this algae in check is the Amano Shrimp. Keeping a crew of hungry Amano shrimps in your tank can solve many algae problems especially the fast growing types like hair algae and staghorn algae. Smaller types of shrimps also eat this algae but not as effective as Amano's.  
  Black Brush Algae/Black Beard Algae              
  This is actually a red algae that grows feathery tufts between 1-4 cm long. The anchoring part of the algae is much smaller in diameter and usually begins to grow as gray patches in the early stages of development. They have the ability to attach tenaciously to various aquarium surfaces including the edges of plant leaves, aquarium glass, filter tubes and even pieces of substrate. It is considered the worst type of algae to get affected with. Once affected by BBA it is very difficult to totally eradicate it from your tank. If left unchecked it can grow and spread rapidly throughout the tank. Fortunately this algae does not cause direct harm to plants. In nature, these epiphytic freshwater red algae are found in fast moving streams which provide a constant, but perhaps low concentration supply of nutrients and CO2. It can be found under extreme lighting conditions or even found in the darkest spots of your tank. So turning off the lights, CO2, and not adding any nutrients into the tank will not rid your tank of this type of algae.  
  If you have red algae in your tank then the most likely reason you got it is probably through introduction of contaminated plants or a bag of fish from a store with red algae. They can enter your tank either as small filaments, water born spores or even in the digestive tract of fishes. Once deposited into a suitable aquarium environment, they will flourish and become a nightmare. Manually cut away and discard affected leaves and/or plants. Equipment can be soaked in 25% bleach. This will slow it down temporarily but will eventually come back. To keep this algae in check, increase your SAE numbers and add some Neritina snails. In severe infestations, its probably less of a headache just to start all over again. A more drastic measure is treatment with copper but this method is not recommended.    
  The best preventive measure is buying plants or fish from reliable stores who dont have red algae. Be cautious when buying or trading plants online... you never know what you are getting. The benefits of buying plants from a store allows you to do a visual inspection of the tank conditions before you buy, on the other hand, buying or trading with strangers you dont get to see that, the seller maybe selling contaminated plants knowingly or unknowingly. It has also been suggested that you can prevent the introduction of unwanted algae spores into your tank by sterilizing new plants in a mixture of one part bleach to 19 parts water for two minutes. The plant should then be rinsed thoroughly and immersed in water containing a chlorine neutralizing solution. Some plants can be subjected to this treatment better than others. Quarantine new fish for a few days until they clear their digestive system will also help.  
  Don't get discouraged by algae. Algae will always be present in aquariums and their control is simply a matter of minimizing excessive nutrients, promoting good plant growth and maintaining a diverse population of algae eaters. Eventually a state of equilibrium will be reached which is unique to each tank where algae growth will be matched by algae consumption. We hope that this article has been very helpful to you and wish you every success in your journey into this wonderful hobby. If you have any question regarding this article please send us an email.