Controlling Algae Growth
Published February 29, 2008
Written by Katherine Barrington
Learn why algae grows in your tank and how to control it.
Algae, algae, algae it is one of the most prevalent problems encountered in the fish keeping hobby. It can be frustrating to conquer and often ruins the look of an aquarium you have spent so much time making perfect. However, algae can be controlled and this article will discuss both the causes of excessive algae growth and the major methods used to control it.
Before we discuss how to eradicate algae, it should be mentioned that some algae growth is perfectly normal in a healthy aquarium. You will never be able to completely stop algae from growing and as long as it doesnt become excessive, it does not harm your fish. Simply wipe off algae from places such as the front glass and it should take a week or two before you need to wipe it off again. If it is growing back within a couple of days, you should read the rest of this article and learn how to properly control your algae.
Also, brown algae (diatoms) are very common with new aquariums going though the nitrogen cycling process. Eventually these brown spots will be starved out of the aquarium if you do proper maintenance.
Causes of Algae Growth
If you want to eradicate algae from your aquarium, it is vital that you understand why it grows in the first place. Algae have certain needs that must be met to survive and flourish. Algae require light, nutrients from the water, and a lack of predators. Without these key components, algae will have a difficult time taking off in your tank and, therefore, it is these areas that you should attack.
Light is a major factor in algae growth. The simple fact is that many people keep their lights on for too long. The lights in your tank should be on no longer than 8-10 hours per day (if you are growing live plants then the recommended length of time is closer to 12 hours, but the addition of plants should offset the additional hours of light more on this later). Timers are very helpful in that they ensure your tank is receiving the correct hours of lights per day. Tanks should also not be placed in direct sunlight. If you place a tank in a window where the sun hits it for several hours a day, you are asking for trouble.
Not only can too much light cause you problems, but too little light can also lead to excessive algae (in particular, brown algae). Therefore, it is not generally a good idea to simply stop turning your light on to get rid of the algae. Instead, you should shoot for the 8-10 hour range.
Also, be sure to change your bulbs every 6-12 months. After this time period, the bulbs will have lost much of their intensity and this can lead to severe algae growth.
Not only is the amount of light important in the growth of algae, but the type of lights you have also dictate its propagation. For instance, actinic lights began in the salt water realm, but are seeing increased use in fresh water systems. However, actinic bulbs can lead to algae outbreaks. There are numerous examples of people who switched out their actinic or 50/50 bulbs and had their algae decrease rapidly. Bulbs that have temperatures of 6500 K or below seem to be the best in terms of not promoting algae outbreaks. If you have tried reducing your lighting period and still are having algae problems, investigate the temperature of your bulbs and see if that is the root cause.
Algae require nutrients in the water in order to grow. These nutrients are usually in the form of nitrates or phosphates. It is, therefore, helpful to test for these compounds if you are having algae problems. If your tests show high levels, first test your tap water to see if it is naturally high in either of these compounds. If it is, you may have to purchase distilled water or treat your tap water (with reverse osmosis, for instance).
If your tap water is not naturally high in nitrates or phosphates, then your tank may be overcrowded or you may be overfeeding. Your fish should generally be fed 2-3 times a day with each feeding lasting a couple of minutes. If you consistently overfeed, the left-over food will make the nitrates spike. The fish in your tank may act like they are starving, but if you are feeding them according to the 2-3 times per day schedule and you see them eating, they are fine. It is vital that you cut down on your feeding if your nitrates become too high (greater than 20 ppm). Frequent water changes will also help reduce the nitrate concentration as will vacuuming the substrate. A thorough vacuuming is often a key missing element in fish maintenance, but it is very useful in getting any uneaten food out of the substrate and removing fish waste.
In terms of overcrowding, a general rule for stocking fish that stay relatively small is one inch of fish per gallon of water. However, this rule does not apply to every species. For instance, a 3 goldfish will produce much more waste than a 3 yellow lab. This rule also does not take into account characteristics such as aggression. It does, however, provide a starting point to see if you are overstocking your tank.
Another way to rob the algae of nutrients is to provide competitors. If you heavily plant live plants in your aquarium, they will use up these nutrients. In the process, they are ensuring that the algae will not have enough to eat.
Before good algae predators are discussed, a common misconception needs to be addressed. Many people rush out to the local fish store to buy a common pleco when they see they have an algae problem. In general, a common pleco is not a good solution to getting rid of algae. The common plecostomus will eat some kinds of algae when it is young, but stops eating algae all together when it reaches a length of around 5-6. From this length on, not only does it not eat your algae, but it contributes greatly to the load on your tank as it produces a great deal of waste and eventually becomes a very large fish. This is not meant to keep you from owning a common pleco if you have the environment to house one and they are a fish you like. It is just meant to warn people that purchase them for the sole purpose of getting rid of algae. There are better solutions that exist and they will be discussed herein.
Stocking predators can be a very effective means of eradicating algae in your tank. However, care needs to be taken when choosing which fish to purchase. Many of the algae-eaters will only eat certain kinds of algae. You need to find out which kind of algae you have first and then you can select a predator to eat it. You also need to see how long the predator will eat algae (see the discussion on the common pleco above for an example of this). Some of the more effective algae-eaters include otos (tend to be the best option for smaller tanks), bristlenose plecos, American flagfish, and rubberlip plecos. Be sure to research these fish before you purchase them to make sure they are suitable for your specific aquarium and eat the right kind of algae.
Minor algae growth is inevitable in your aquarium. In fact, the look of a tank is often enhanced by the subtle growth on rocks or the back glass. The problems occur when the algae starts to take over your tank. If you encounter this problem, read over the suggestions in this article. Most algae problems can be solved by reducing the hours of light, changing the temperature of the light, reducing the amount of food, reducing the number of fish, adding live plants, or adding predators. There are some types of algae blooms where more extreme methods needs to be used, but the recommendations in the article will help in the control of most algae.
For additional information, refer to the following web pages:
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