I’m very sorry to have to tell you that if you have fish in water, you will have fish tank algae. There is no way around it. Fish produce the perfect fertilizer for algae, nitrate. You may not be able to avoid it, but there are ways to mitigate it.
However, remind yourself that fish don’t care about algae, people do. Just because your tank is a little bit green does NOT mean that you are a terrible fish parent. It means your tank is healthy! But this does not apply to a tank so thick with slimy green scum that you cannot even see your fish.
Algae is a single-celled plant that can replicate very quickly. It may clip together with similar cells to produce hair or string algae, or it may stay singularly suspended in solution. During the daylight hours, algae converts sunlight and carbon dioxide into oxygen and water, a process known as photosynthesis. However, once the sun goes down, the algae start to use the oxygen in the water to respirate, converting oxygen back into carbon dioxide. This can produce respiratory acidosis, where the carbon dioxide levels start to drop the pH. In tanks that are very, very green, the algae can out-compete with fish for oxygen AND start to decrease you pH. As long as you kH or alkalinity is sufficient, your pH will not drop drastically. Having sufficient aeration in your tank will make sure there is plenty of oxygen to go around.
So, how do you keep fish tank algae from getting out of control?
- Keep up with your regular water changes. Algae uses nitrate as a food source, so by limiting your nitrates by doing regular water changes, you will keep your algae in check.
- Try to minimize direct sunlight on your tank. Not only will it keep your temperature from spiking, removing sunlight will help keep the algae from growing too quickly.
- Scrub your tank walls regularly. Once the algae is loosened and sent into the filter, it will die from lack of sunlight.
- Out-compete the algae with aquatic plants. Aquatic plants work the same as algae, just on a larger scale. For everything you want to know about aquatic plants, check out our webinar on Plants in Fish Systems. They will not rectify the entire problem, but will give minor assistance.
What should you not rely on to “treat” fish tank algae?
- Chemical additives are rampant on store shelves. These have NOT been tested on all species of fish. They are NOT controlled by any governing body.
- UV lights only catch particulates in suspension. They will have NO affect on any algae trapped to the sides of your tank. But they will help zap it if you scrub.