A Basic Look on Algae Problem in Planted Freshwater Tanks



A neatly designed, well-planted tank is the dream of every aquarist. You dream yourself chilling out while drinking your coffee in front of a water forest, fish swims evenly, bubbles are racing to reach up and plants with all tones of green shading the gravel of your aquarium.

But wait, what is that green thread like thing coming out of the leaves! After a quick search on the internet, you discover that it is the algae.  Along with what you read and the effect of the documentaries you watch, the idea of something eating other thing creating the food chain in nature just comes out. You rush to your local pet store to buy some algae eating fish and ask about your algae problem to the seller. Although he looks sorry about your puzzler, in fact, he is one of the happiest sellers in the world. Right now you are a potential customer who is willing to buy anything to be offered regardless of its price not to exterminate one of his or her greatest dreams in life. You come home with a couple of baby common plecos and some drops for killing the algae. Everything looks good now; you’ve solved the problem, haven’t you? Don’t be that sure; this could be just the beginning of a nightmare.

Now let’s look for common solutions for algae problem that are applied by hobbyist;

1. Adding algae eaters into the tank.

Indeed this idea is not that bad. You can control algae with some effective algae eating animals. If you search online, there are numerous options to have. Oto cats, ancistruses, Amano shrimps, red cherry shrimps, apple snails and you name it. It is inevitable that these critters consume algae as a part their diet.

a. The first common awkward thing that I see all the time is adding common baby plecos (Hypostomus Plecostomus) which are also known as suckermouth catfish or plecostomus to the tank. As an omnivorous, despite this fish eat algae when it is younger, as it grows up, it will lose its interested in algae. Since it is a fast-growing species, it would need plenty of food, and it can’t be expected from an omnivorous animal that it will gather all its nutrition from the algae. According to Wikipedia; Hypostomus Plecostomus can reach  50 centimeters (20 in), and they do it easily. Think that a 50 cm long armored suckermouth catfish are swimming inside your tank, knocking out everything and sucking your lovely fish at night while they are sleeping.

b. The second thing is overstocking the tank -even with algae eaters-. The more you add fish, the more you get excess of organic materials, and this is what algae like. When you have extra fish in your tank, you need to pour more food in the tank, and this means additional waste. This is like the domino effect. The nitrate which is produced by the excess organic material is what algae want and now this is its turn to carry out its lifelong dream. Moreover, competition among the fish twitches other unwanted issues.

2. Using chemicals to get rid of the algae:

There are plenty of products in the market for algae treatment for home aquaria, and they all promise to solve it in a very short time.

The problem adding the chemicals in a tank reminds me of playing Russian roulette with more than one bullet. We are trying to build a balance in a small environment by copying nature. There are too many environmental factors in the nature that helps to keep its balance. Unsurprisingly we are not aware everything nature does to keep its balance. Accordingly, think that you are trying to find this complicated balance at home. Who knows maybe algae bloom is the nature’s treatment for excessive organic waste. Nonetheless, it is not possible to copy the nature flawlessly in such a small container with artificial supplements.

Moreover as aquarists; we always want to see the best scenery of the nature not the problematical expression. There are too many inputs in water chemistry that I cannot mention all of them here such as PH, KH, GH, hardness, nitrate, nitrite, acidity, dissolved oxygen/carbon dioxide and so on. These chemical reactions are all connected to each other. Once you lose the control, it is not easy to accumulate everything in one piece. Additionally, copper-based algae treating chemicals would certainly disturb your sensitive fish like loaches, plecos, tetras and even can kill your all invertebrates.

Now let’s take a look at what we might be making wrong so algae is growing excessively


1. Light

a. Direct Sunlight to the aquarium.

Exposing your tank to the direct sunlight would certainly promote algae growth in your tank. Your tank should not be showing to direct sunlight even short periods of time during the day. You should choose or replace the location of your aquarium accordingly. I know that some spouses or parents don’t want an aquarium at home and our poor hobbyists have to put it in the balcony and they are desperately looking for algae treatments. I have witnessed it happening to one of my friend. Not me, one of my friend J.s

b. Improper lightening periods.

If your tank’s lights are turned on first thing in the morning and turned off just before you go to bed, this might be causing the unwanted algae growth. Connect a timer between the plug and light to control the timing of the light you are providing to your tank. Ten hours a day is enough for a planted tank on condition that you adjust the light with some breaks during this period. For example, the lights are on for two hours when you wake up and one hour rest, again two hours on and two hours off. You can regulate this timing according to your schedule. No worries if you want to watch your tank when the lights are off, timers have a button to disable the timer and turn on the lights. This procedure will certainly discourage the growth of algae.

2. Lack of Water changes and maintenance.

This is another possible reason of excess algae growth.

a. Do at least 10 % weekly regular water changes. The rain refreshes the water in the nature therefore we mimic the nature by doing water changes. Try to get the water from the bottom of the tank to be able catch the nitrate causing materials such as fecal matter, dead fish, uneaten food and dead plant material.

b. Scrape the glass at least once a week to prevent algae on the glass. There is a type of algae that resides on the glass that is not easy to remove once they cling there. You can do scraping with the magnetic scrapers, soft sponges or credit cards by placing your hand inside the tank.

c. Clean your filter media regularly as it is directed in your filter’s manual. Choosing the proper media may help to reduce the phosphate/nitrate levels of your water so the algae.

3. Overfeeding,

Excessive feeding is one of the most common causes of the generating algae nutrients which are phosphate and ammonia. I know that it is fun to watch while your fish is feasting on some tasty bits but to discourage the algae you should minimize the feeding. Furthermore this may encourage your fish nip the algae more than usual.

4. Excessive usage of fertilizers,

While it is necessary to use proper fertilizers in planted tanks, if it is used more than enough the phosphate, nitrate and other minerals inside the fertilizer would definitely cheer up the algae in your tank. There is a saying “Poison and medicine is just about quantity”. As a result if you decide to use fertilizers do remember the rule of everything is in moderate.

Another common mistake that is made by a hobbyist is using the fertilizers that are for houseplants. They are mostly full of macro elements like ammonia/urea which is also toxic to fish and trigger algae as well.

5. Choosing all slow growing plants/not enough planting,

Plants use the macro and microelements that are present in the water. If there are too many elements that are derived from excess organic materials, fertilizers and your tap water and they are not consumed by your plants in the aquarium, algae will use it for growing. Dense plantation and selecting some fast growing plants would definitely help you fight with algae.

6. Not sterilizing new plants and fish,

a. When you buy a new plant, you should sterilize it before you put it in the tank. Sterilizing not only prevents transferring algae to your aquarium but also helps to exterminate diseases and invertebrate eggs on the plant. To prepare for the disinfecting of aquatic plants, prepare 1 Liter (0.3 US G.) of lukewarm (25°C (77°F) ) clean tap water and drop 10 mg of crystals (Potassium permanganate) into it and stir until the solution turns deep blue/purple.

Be careful as this solution will stain and is toxic to life.

Dip the leaves of the plant into the solution for 10 minutes, being careful not to dip the roots of the plant in it. Then rinse off thoroughly. This will kill live snails as well as snail eggs and parasites [1].

b. When you get a new fish, do your best not to pour the water you bring fish into your aquarium. There is a simple way to do it. Pour a small glass of your own tank water into the bag. Repeat it every fifteen minutes, and then you can take the new fish with a net to add it to your tank.



Consequently, you cannot solve your excess algae problem completely either by having a group of common plecos or lots of different species of algae eaters nor adding expensive chemicals to your system. The algae problem is the result of something that you are doing wrong. For instance, killing all the algae with some medication all at once is the same as taking a painkiller after you hit your head on the floor. The painkiller may decrease the pain, but the main cause is still in your head. Perhaps you broke your skull or harmed some part of your brain. What I try to say is the algae problem is an outcome, you must find the source of it. Algae is everywhere, they are even in the space [2]! It is not possible to get rid of algae completely. You should learn how to keep it snooze.

Basically; adjust your lights, do regular water changes, stay away from sunlight, house proper algae eaters and some fast-growing plants, do not overstock your tank, minimize the feeding than everything would be okay.



 [1] http://www.theaquariumwiki.com/wiki/Potassium_permanganate

 [2] https://www.iflscience.com/space/marine-plankton-found-surface-international-space-station/

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