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Algae: causes, identification and treatments...
Beginners as well as experienced hobbyists have, at one point or another, all had to deal with the undesirable effects of algae. Algae are normal and are found in a variety of biotopes in the wild. There are many different types of algae. Some are more harmless to the aquarium biotope than others. Some appear because of high nitrate or phosphate, some are signs of low level of nutrient, but most of them are related to water quality. In this article we will focus on the main variety of freshwater algae. We will try to understand their cause as well as potential treatments and prevention. This article is not intended to be a complete directory listing all types of algae but more a comprehensive guide for the hobbyist to understand what are the causes, consequences and solutions to a problem that is sometimes no more than just a sign of well established biotope.
Karen A. Randall divides algae types into two groups. One she classifies as “normal” and others more specific types of algae. As we stated in the introduction, numerous hobbyists have had to deal with algae at one point or another. Algae are normal, even in good conditions. Because there is no such thing as perfect water conditions, algae will always find source of nutrients to aliment their growth. In a heavily planted tank, a number of nutrients like iron and CO2 have to be added for the plants to develop and thrive. Aquarists tend to forget that algae are plants themselves and benefit from these nutrients as much as the plants do (sometimes even more). Excess in nutrients are then absorbed by algae which can proliferate at an incredible rate.
Kaspar Horst likes to emphasis the fact that this phenomenon is also true when nutrients are low. In such a case, algae use part of the plants nutrients to survive, making them stronger to the detriment of other plants. Number of factors can be attributed to the growth of algae but dosage of nutrients seems to be one of the main one for the “normal” algae type.
One should therefore provide the plants with the right amount of nutrients. Randall includes a large part of her article explaining the aquarist should “meet all the needs of the plants while leaving very little excess nutrient for algae”. Sounds easy, but even experienced hobbyists with years of practice and observation would have difficulties to add the exact right amount of nutrients without adding enough or too much for the algae to develop. Algae are normal and the best way to fight against them is to prevent them. Randall reminds us that nitrates and phosphates have to remain low. Therefore frequent water changes must be done. Fish must be carefully fed so no excess in food can cause a raise in nitrates (and nitrites). Lighting, CO2 and nutrients must be well balanced. One should be vary careful when adding CO2 to the tank water.
If it is too late to prevent, “natural treatment” is the next step. Numbers of fish are well known to eat and get rid of algae. However there are not all effective on every kind of algae. For “normal” algae, Randall recommends Otocinclus. They are great algae eaters but must be kept in large quantities to make an effective job. Flying foxes seem to also do a great job at eating common algae.
Brown Algae (Diatoms: single cell algae) are often found in newly setup tank where the level of nitrates and nitrites are quite high. In older, established tanks, their presence is often due to low lighting or high level of silicate. Otocinclus seem to be of choice to eat this kind of algae. Of course, because of their small size, it is recommended to get them in large enough quantity to keep up with the algae growth. This kind of algae sets up on most surfaces (rocks, substrate…). Higher level of lighting or controlling the level of silicate (depending on the cause) should take care of brown algae. In newly setup tanks, brown algae seem to go away when the tank gets established.
Red algae appear with high level of nutrients. There are too different types of red algae. The long thread kind, also called beard algae, and the short thread kind called brush algae. Neil Frank wrote a great article on the causes and treatment of red algae growth. For him, a tank can be contaminated by red algae because of several reasons.
First, algae are everywhere. They can be present as full grown plants or as spores in water. Transferring plants from a tank to another can easily cause red algae infection. As Neil underlines, spores are transferred very easily through water, plant leaves and even fish (trace of red algae can be found in fish stomach, it is therefore a good idea to quarantine your fishes before adding them to your community tank).
High level of iron favors red algae growth, because algae absorb the iron that is in the water. Neil Frank reminds us that this problem does not imply a decrease of iron in water but more a change in the way iron should be supply to the plants. Indeed, algae absorb iron that is in the water. If plants are supplied with iron through their roots/substrate, part of the problem has been taking care of. Fish excrements play a good role of providing iron to the plants through their roots. Some more drastic treatments include the use of bleach or copper but we won’t discuss them as we are still septic on the consequences these can have on the plants and fish.
Blue/Green Algae, also called slime or smear algae are Cyanobacteria. Their slimy texture often covers the substrate of the infected tank and can spread almost over everything. Randall reports their presence in high PH and alkalinity waters.
This type of algae is sometimes very smelly and can also be caused by a lack of oxygen. As Horst suggests, algae is often a good indicator of lack of maintenance. This is the case for blue/green algae. Erythromycin seems to be the best way to get rid of them as no fish seems to eat them (Karen A. Randall). 200mg for 10 Gallons is the appropriate dosage.
Green water, also called algae bloom (single celled algae) can be caused by a sudden change in the biotope of your aquarium and high nitrates. Newly setup tanks are also prone to this kind of algae. This kind of algae is free floating which turns water green and blurry when widely spread. It seems to disappear with improvement in water quality. One way of getting rid of green water is to introduce daphnia. Daphnia eat the tiny algae and are then eaten by the fish. Paul Krombholz explains his experience with this method in the krib forum. Other interesting articles about green water are available here.
Another approach by Randall is to turn the lights of the tank off for a week. She seems to have had pretty good results at getting read of green water with this method without damaging her plants too much. If using this method, we recommend adding some source of oxygen (air stone…) for the fish not to suffocate.
As we discussed previously, algae are very common in aquarium and are almost impossible to prevent totally. A little algae is normal and I almost feel like saying that they could be a good indicator that things are done right (if they are not in excess). Different types of algae require different treatments. Fish, shrimps and other algae eating species should be the first to be considerate in the fight against algae. Natural treatment is the only one used in the wild and fighting algae with bleach or other drastic method must be done very carefully (click Here if you want to learn more about these methods). After all, natural look is what most hobbyists want to achieve in their aquarium, algae is part of it!
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