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How To Grow Algae On Rocks In Your Aquarium Fast!

Although many people within the fish keeping hobby, especially beginners will usually do better when trying to avoid algae growing in their aquariums as it allows them to build up their core aquarium keeping skills without having to worry about additional potential problems from the algae.

That said though, with aquascapes becoming increasingly popular, especially the ones that feature some type of algae on them, we have noticed a spike in people reaching out and asking questions about how to grow algae on rocks recently.

There are a number of different strategies that you are able to use to your advantage when looking to grow algae on rocks with most of them being very easy.

In most cases, you can simply add your algae spores of choice to your tank and make sure that you have suitable rocks for the algae to take hold on and then just let the algae grow.

In some aquarium setups, you may have to use a fertilizer product to help the algae grow but this is rare.

If you are looking to use a fertilizer product to help increase the growth rate of the algae in your aquarium tank then we would highly recommend that you go with Flourish due to its low price and excellent reputation within the aquarium keeping hobby.

Not only can it increase the growth rate of your algae on your rocks but it can also be used to help boost your algae allowing other factors in the tank such as water parameters or lighting to be less than optimal but still encourage growth.

Does Algae Grow On Rocks?

Algae can and will grow on many types of rocks that you add to your aquarium, often with you not having to take any further action to get the algae to grow.

Keep in mind that there are some rocks that are not suitable for algae to grow on due to their mineral composition of natural pH of the rocks but in the vast majority of cases, these rocks should not be kept in your aquarium anyway as they can cause problems with your water parameters.

The most common rock that should be avoided in an aquarium where you are actively trying to grow algae is limestone.

Not only will limestone reduce the excess iron in your aquariums water that many types of algae require but limestone can cause a wide range of other problems in your aquarium for algae reducing its ability to grow and in some cases, totally preventing the algae from growing at all.

Other rock types to avoid in your aquarium where you are wanting to grow algae include Dolomite, Marble, and Geodes too but there are a few less common rocks that can cause problems for your algae.

In our opinion, river rocks are one of the best options for a base rock to grow your algae on within the aquarium keeping hobby as they are safe for algae but also have a flat surface allowing the algae to spread with an even light distribution offering optimal conditions for the algae to grow at a healthy speed.

How To Grow Algae On Rocks In Your Aquarium Fast!

It is usually very easy to grow algae on rocks in your aquarium as most aquarium setups will offer optimal conditions for most types of algae.

The most common mistake that people make when trying to grow algae on rocks is to use an unsuitable rock but opting to use some flat sided river rocks will be enough to prevent this and offer the algae plenty of direct light to grow.

The majority of people who will be reaching out for advice on growing algae on their rocks will be new to the aquarium keeping hobby and often don’t have any water flow in their aquarium removing this potential problem from their setup too.

If you are running an aquarium that does have a water flow pump them a low level of water flow is usually the best option if you are intentionally trying to grow algae but still water with no water flow is better.

Different types of algae tend to thrive in different light intensities so you may have to research the best lighting intensity option for the specific algae that you are trying to grow in your aquarium.

That said though, the majority of algae types will do well on a moderate light intensity but their growth rate may be slower for some types of algae that prefer a high light intensity but even then, they should be fine with a moderate light intensity if you use something like Flourish to offer them all the nutrients that they require.

How Long Does It Take For Algae To Grow On Rocks?

The growth rate of algae will depend on a number of factors in your aquarium but in optimal conditions, most types of algae can usually double in mass in a single day.

This can be expected to continue until the algae reachest a level where it starts to have problems with maintaining its light exposure or nutrient levels causing growth to rapidly decline.

This is the algae natural way to try and regulate its growth to prevent it from over growing and ending up perishing. Just keep in mind that many types of algae can be more aggressive with their growth than other live plants that you have in your aquarium.

This can sometimes result in your other live plants having problems getting the light and nutrients that they require in your tank due to algae taking up so much of the essentials.

You also have to factor in the natural growth rates of different types of algae too. Some algae is naturally slower than others even when living in perfect conditions and a very small number of algae types will grow at a rate slow enough to not double their mass each day.

So, for the most part, expecting the mass of the algae in your aquarium growing on your rock to at least double each day when newley added to your tank is a solid expectation to aim for.


That brings our article going over how to grow algae on rocks in your aquarium to an end. We hope that we have been able to offer a few pointers but it really is very easy to grow algae in your tank due to the majority of setups offering perfect conditions for algae to grow. As we mentioned back at the start of the article, the most common issue that we see time and time again is people trying to grow algae on a rock that is not suitable such as limestone but other than that, it is a beginner friendly project that really shouldn’t be problematic.