Nearly every fish keeper will suffer from problem algae at some point. It is important to remember that algae is just a symptom of an underlying problem. Algae growth can be useful for helping to understand more about the way your tank works.
Why does my tank have algae?
Algae is a very primitive type of plant and like all plants it needs three things to survive. Light, water and nutrients. Obviously we cant take away the water so our focus should be on the lights and nutrients in the tank.
- Does the aquarium receive direct sunlight? This is one of the most common causes of algae growth on glass and ornaments.
- If you use fluorescent lights, when were they last changed? If they are more than a year old they may be giving out the wrong type of light.
- Over feeding is often the cause of algae blooms. Too much food will raise your phosphates which will cause algae to grow.
- Incorrect or infrequent water changes allow waste to build up not to mention feed nuisance algae.
How do I get rid of it?
The first thing to do is test your water using a reliable test kit like the NT Labs Aquarium Lab Multi Test Kit. This will show you if the waste levels in your tank are contributing to the algae growth. Too much Nitrate or Phosphate in a tank will act as fertiliser for algae.
Over feeding is more common than you think
- Almost everybody overfeeds their tank. Fish are cold blooded so they don’t need as much food as you might think. Choose a high quality fish food and then feed only once or twice per day, as much as your fish will eat in one or two minutes. If you are using a flake food, crunch it between your fingers slightly so that your fish can easily eat it.
- Remove uneaten food after feeding the fish. If left, it will break down in to waste that will feed algae.
- Over feeding is not always the problem. It could be that your aquarium maintenance routine needs changing. Aim to change 15 – 20% of your water every week. Changing more water will have negative effects as you risk upsetting the balance of your tank and killing off beneficial bacteria. You should use an aquarium gravel cleaner because nearly all of the waste in your tank is trapped in the substrate.
Water changes must be done correctly
- Changing water from the top of the tank will not remove waste as the water is relatively clean.
- Once you know that your water is low in nutrients it is time to look at the lighting. If your tank receives direct sunlight, this will most likely cause problems. Either try moving your tank to a more shaded part of the room or keep curtains and blinds closed for longer. If light is hitting the sides or back of the tank, consider adding an aquarium background to block some of it out.
- The last thing to check is often overlooked. How old are your aquarium lights? Fluorescent bulbs will give out the wrong type of light once they are about a year old. If your tank has this type of light, it may be telling you that it is time to change the bulbs. Good quality LED lights like the Zetlight do not tend to suffer from this problem and have a low running cost.
Keeping algae at bay.
A small amount of algae in a mature tank is natural as it is a sign that your filter is working well and converting ammonia and nitrite into relatively harmless nitrate. It is unsightly though and best removed.
- Test your tap water regularly as many areas of the country have quite high nitrates and phosphates. If this is the case where you live, you may have to add products to your tank regularly to help combat it. Phosphate removers and Tetra Nitrate minus are good examples. You can use Reverse Osmosis water instead of tap water as it contains no organic nutrients what so ever.
- Make sure that you only use the best quality fish food. Cheap fish foods often have higher amounts of indigestible ingredients and these will end up in your water.
Get help from a clean up crew
- Consider adding algae eating fish or snails to your aquarium. Fish such as Siamese Algae eaters and various types of plecostomus will graze on most types of algae. Whichever species you choose you should always check what size they will grow to as some can get huge! Nerite snails are a more recent addition to our hobby and have made themselves a great name as algae munchers. These small (up to 1″ shell) snails can be added to your tank at a stocking level of one per 15 litres and will usually annihilate green algae. They are so popular because unlike many snails, they won’t graze on live plants and they are difficult to breed so you wont end up with a plague of them.
The most important thing to remember is not to panic. Whatever the reason behind an algae bloom, it is almost always a relatively easy problem to fix. Once you understand why algae grows you can keep it away and enjoy your tank for much longer.
Download this guide as a PDF here How to get rid of aquarium algae