6 Common Questions On Algae Growth – Answered! 6

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Algae Growth

This probably is the most burning question among hobbyists,

“Why and how does algae grow in my aquarium?”

Time and again we see algae entering our tank out of nowhere causing a lot of nuisance and disrupting the whole living environment of our marine life.

It’s not ideal to have menacing algae in the aquarium, although it still is alright to have a small amount of macroalgae that actually benefit the marine ecosystem.

Note: This is the final part of the Saltwater Algae Control series, the rest of the series can be found here:-

Why Do You Need To Know About The Science Behind Algae Growth?

In order to get to the root of the problem, the uncontrolled growth of algae in our aquarium, we need to go deep inside and take a good, hard look at why and how exactly do algae grow in our aquariums. Once we’re able to answer this question tackling algae will be much more easier and much less of a hit and miss scenario.

Algae Under The Microcope

Algae Under The Microcope (Wikipedia)

Just like any other problem it is important to understand the cause of it and tackle it from there. Giving you an understanding of the problem will allow you to make your own decisions without having to rely on other people or sources.

This is also largely beneficial in the long run where you’ll have a good understanding of how algae enters your aquarium and how do they spread. This way you wouldn’t have to blindly follow what anybody suggests about algae control and you’ll be able to think on your feet as to what has to be done to control the algae in your aquarium.

How Fast Does Algae Grow In Your Aquarium?

Before we get to why do algae grow in our aquariums, let us first take a look at the pace of growth of algae in aquariums so that you get an understanding as to how much time you have before things really get out of hand.

The news isn’t the best folks; algae grows at a very rapid pace once it gets into your aquarium. It can grow three times its size within the matter of a couple of days if quick measures are not taken to control the algae.

Overgrown algae

Overgrown algae (source)

One of the main reasons for such rapid growth of the algae can be attributed to the reason the algae gets into your aquarium in the first  place which is it’s ability to adapt and its ability to get the most out of what it available.

What exactly happens is that although you don’t intentionally plan to grow any algae in the aquarium, the algae being such an adaptive organism gets into the aquarium from bacteria already present in the aquarium and begins to grow from what resources that are available to it inside the aquarium.

It’ll make complete use of those resources to grow and flourish in the environment. Algae have a parasitic characteristic of sorts which allows them to flourish in aquariums; the algae rapidly absorbs the excessive nutrients from the water (before it can be absorbed by another plant) which helps the algae grow.

When Should You Be Worried About The Algae In Your Aquarium?

When you see a small amount of algae in your aquarium there’s no reason to panic unless you haven’t taken preventive measures to keep the algae growth in check.

If the algae continues to remain at those low levels and isn’t really interfering with the other living organisms in your tank, there’s no real reason to worry.

Red Algae/Macroalgae

Red Algae/Macroalgae

You should make sure that the algae isn’t taking in all the nutrients which is required by the plants in the aquarium as well.

Algae are naturally a part of aquatic life whether it’s in oceans, seas, rivers, lakes or even ponds.

They are actually beneficial when present in small amounts because they absorb the excess nutrients present in the aquarium and they also work as a great source of food for certain types of fish. So, as long as they are in small quantities, not growing on your plant leaves or walls you shouldn’t be too bothered.

But you should make sure you keep the algae growth in check or else a sudden algae outbreak can cause quite a problem, especially because before you know it algae can take over your aquarium.

How Does Algae Grow In Your Aquarium?

As I’ve mentioned previously in this article, algae can grow in your aquarium because of the already present bacteria. The bacteria in your aquarium comes from fish as well as uneaten food.

Just like we humans need good bacteria to survive (think curds/yogurt), fish also do need good bacteria to survive. This bacteria when given the right conditions can lead to the growth of algae. This happens with a reaction of carbon dioxide and light in the water.

Why Do Algae Grow In Your Aquarium?

Now, getting to the question all of us as hobbyists wonder about, why do algae grow in our aquariums? Let’s break it down into the basic factors that influence the growth of algae after which we’ll take an in-depth look at the various elements that lead to the growth of algae in our aquariums.

There are three elements that are directly linked with the growth of algae in aquariums:-

  • light,
  • nutrients and
  • temperature of the water.

Now that we’ve narrowed down the basic three elements that cause algae to grow in our aquariums, let us take a closer look at what are the broader factors that affect the growth of algae:

1. Lighting Of The Aquarium

Whether it is the natural lighting that comes from the room or whether it is the lighting that comes from the aquarium, the lighting of the aquarium plays a crucial factor in the growth of algae. Algae, just like any other plant, requires light in order to photosynthesize which is key to its survival. When you give the aquarium excessive light then you’re inviting the algae to breed and spread in the aquarium.

You can’t have lighting for more than 8-10 hours a day, in whatever form. Having lighting of over 10 hours a day will allow the algae to flourish in the aquarium and 8-10 hours of lighting is enough for the plants in your aquarium to photosynthesize while not allowing the algae to take advantage of it and spread.

Ideally, you should use an automatic lighting timer which you’ll get at your local pet/fish store which controls the number of hours that the aquarium gets light and you can set it to 8-10 hours. That way you don’t have to be bothered about having to remember to switch off the aquarium’s lighting manually.

2. Excessive Nutrient Buildup

Nutrients are the key to survival for any living being right from terrestrial animals, aquatic fish to algae. Without nutrients an organism cannot carry out its bodily functions and the lack of it for a sustained period of time can lead to the death of the organism.

Algae, just like any other organism are reliant on nutrients and when it’s abundant they spread like wildfire (the irony!) in your aquarium. When the nutrients present in the water are controlled, so is the growth of the algae.

The lesser the nutrients available freely for the algae to absorb, the lesser will they be able to reproduce and grow. The key here is to limit the the amount of nutrients in your tank that come from various sources.

3. Temperature

With an increase in temperature, the growth of algae also increases. An increase in temperature means that you’ll see higher nutrient levels in the water which allow for the rapid growth of algae. At higher temperatures, there are fewer microscopic organisms as well that feed on algae, leaving excessive algae in the aquarium.

4. pH Levels

Higher pH levels create a perfect environment for algae to grow in. If pH levels aren’t maintained at the right levels then you can see a spurt in the growth of algae.

It is important to keep the pH levels within the desirable range and to have a testing kit at hand to check the pH levels regularly to ensure that it is at the prescribed levels.

Learn how to "manipulate" pH levels, naturally - here

Learn how to “manipulate” pH levels, without adding chemicals – here

The higher the pH of  the water (alkaline) is the more the conducive it is for algae to grow, so increasing the acidity of the water will reduce the algae growth in your saltwater aquarium.

5. Silicates In Unfiltered Water

Diatoms flourish when silicates are present in the water. The structure of diatoms primarily consists of silicates and its presence along with low sunlight makes it easy for it to grow in aquariums.

This is one of the reasons why we advise hobbyists to balance the amount of light given to your aquarium through the day because some algae require low light conditions in order to thrive.

Getting back to the silicates, they get into your aquarium through the water source. Many hobbyists tend to use unfiltered tap water which tends to contain a lot of silicates in it. Due to this high level of silicates, diatoms flourish when aquariums are filled with tap water which is why it is advisable to use filtered water.

6. Limited Plants In The Aquarium

Having very few plants in the aquarium can leave a lot of nutrients “unattended” to which can lead to the growth of algae in the aquarium.

If there’s a healthy number of plants in the aquarium then the excess nutrients would be consumed by the plants for its growth. When there aren’t too many plants these nutrients become stray and feed the growth of algae in aquariums.

How To Prevent And Control The Growth Of Algae In Your Aquarium?

Now that you’ve got a good understanding of how the algae got into your aquarium in the first place, you’ll be able to tackle your algae problems better.It is important to keep algae in the aquarium under control so that it does not adversely affect the marine life in the aquarium.

Controlling Algae Growth

Is This How You Control Algae Growth? – Don’t be THAT guy!

I’ve written another post, “Saltwater Algae Control: The Ultimate Guide” which will give you the ins and outs of the different types of algae you’ll find in your aquarium, which of these are harmful, how you can identify them and most importantly how you can prevent and control their growth.

I think after reading this article you can finally get some good sleep tonight because the one question that’s always been on your mind has finally been answered, “How in the world did that nuisance algae get into my aquarium?!”

Share The Knowledge

I hope that this will be of great use to you and you will use this information to make informed decisions about the algae in your aquarium. We’d love to hear from you on your experiences with algae and how you tackled it, so please do drop a comment in the comments section below.

If you liked this article and would like to hear from us on exclusive tips and information on aquariums please sign up to our smashing newsletter on your right-hand side.

Until next time, goodbye fellow hobbyists!

About Dennis Hanson

Dennis is an experienced aquarist with many years of knowledge and experience in keeping successful tanks. He also has no relations to the pop group Hanson.

6 thoughts on “6 Common Questions On Algae Growth – Answered!

  1. Reply SantaMonica Feb 24,2014 2:44 am

    Hi Dennis… here is a little writeup I have about Export… maybe it will help the folks…

    Nutrient Export

    What do all algae (and cyano too) need to survive? Nutrients. What are nutrients? Ammonia/ammonium, nitrite, nitrate, phosphate and urea are the major ones. Which ones cause most of the algae in your tank? These same ones. Why can’t you just remove these nutrients and eliminate all the algae in your tank? Because these nutrients are the result of the animals you keep.

    So how do your animals “make” these nutrients? Well a large part the nutrients come from pee (urea). Pee is very high in urea and ammonia, and these are a favorite food of algae and some bacteria. This is why your glass will always need cleaning; because the pee hits the glass before anything else, and algae on the glass consume the ammonia and urea immediately (using photosynthesis) and grow more. In the ocean and lakes, phytoplankton consume the ammonia and urea in open water, and seaweed consume it in shallow areas, but in a tank you don’t have enough space or water volume for this, and, your other filters or animals often remove or kill the phytoplankton or seaweed anyway. So, the nutrients stay in your tank.

    Then the ammonia/ammonium hits your rocks, and the periphyton on them consumes more ammonia and urea. Periphyton is both algae and animals, and is the reason your rocks change color after a few weeks. Then the ammonia goes inside the rock, or hits your sand, and bacteria there convert it into nitrite and nitrate. However, the nutrients are still in your tank.

    Also let’s not forget phosphate, which comes from solid organic food particles. When these particles are eaten by microbes and clean up crew, the organic phosphorus in them is converted into phosphate. However, the nutrients are still in your tank.

    So whenever you have algae “problems”, you simply have not exported enough nutrients compared to how much you have been feeding (note: live rock can absorb phosphate for up to a year, making it seem like there was never a problem. Then, there is a problem).

    So just increase your nutrient exports. You could also reduce feeding, and this has the same effect, but it’s certainly not fun when you want to feed your animals :)

  2. Reply Clarissa Sanchez Sep 28,2016 12:51 am

    I have a science project on algae growth. How long do you think it would take for algae to grow in mineral water? Like, the amount of time it would take…

  3. Reply Clarissa Sanchez Sep 30,2016 4:44 pm

    this website is awesome it answered all my questions on algae transformation!! Thanks!!!!

  4. Reply Madison Cuava Sep 30,2016 4:46 pm

    I have a science project on different types of algae that grows in the ocean..What different kinds do you think would grow?

  5. Reply Charlotte Oct 18,2016 10:00 pm

    I saw a source like from a photo, but do you have a source link for the facts you gave?

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