Hammer Coral Growth Rate

So, your hammer coral has just arrived, and now you are wondering how long it is going to take to grow into a fully established coral. You are not alone… One of the most exciting parts of owning a reef tank is the satisfaction of successfully growing corals. 

Hammer corals are one of the most popular large polyp stony (LPS) corals known to man. Their beautiful colorful tips and funky-looking shapes are only two of the many reasons why you should add them to your aquarium. 

With proper care, hammer corals can easily form new heads and expand their bases, growing into fully established corals, which is the ultimate goal in coral husbandry.

So, with that being said, let’s dive straight into typical hammer coral growth rates, and what you can do to promote their growth. 

How Fast Do Hammer Corals Grow?

Hammer corals usually start growing slow, but once they have fully settled into your aquarium, some hammers are known to grow like weeds. 

For example, if you are looking for slow controlled growth, a wall hammer coral is what you should be looking for. But, if you want a faster-growing hammer coral, then branching types will produce heads much faster. Branching hammer corals also have an exponential growth rate, which is also why they are usually more popular over wall varieties. 

With that being said, whether you go for a wall or branching hammer coral, you cannot expect it to grow overnight…

Corals need time to settle into their home before they can start to grow to their full potential. This initial period also allows your hammer coral to focus on growing its calcium carbonate skeleton, which requires a lot of time and effort!

Most of the time you will see good coral growth rates within the first few weeks to months, while some hammer corals can take a couple of years to fully establish. However, there are a few things you can do to promote faster and more importantly, healthier growth!

6 Ways To Promote Faster (& Healthier) Coral Growth

Hammer corals are fairly challenging to care for, therefore it is important to meet your coral’s needs for optimal growth. There are a few things YOU can do to make them feel more at home and these include the following:

1. Allow Enough Space Between Corals

Long story short, hammer corals are aggressive. 

Your hammer coral contains specialized stinging cells called nematocysts, located at the tip of its long sweeper tentacles. At night, hammer corals come out to play, extending their tentacles as far as they will reach. While this is a good mechanism for warding off predators in the wild, in your aquarium the sweepers can cause issues. 

As your hammer coral grows and spreads out, it will sting any encroaching corals to allow it to continue growing. Having to warn off other corals can be exhausting for your hammer coral, so always allow plenty of space between corals so that your hammer can reach its full growth potential. 

2. Provide Sufficient Water Flow

Your hammer coral requires a random and indirect, moderate water flow to grow. Water flow is critical for providing your hammer coral with oxygen and flushing away waste. Sufficient water flow also allows your hammer to catch nutrients from the water, which are required for growth. 

Maintaining the correct level of water flow is vital. For example, if your water flow is too powerful, you risk tearing your hammer coral’s polyps, which can stunt their growth and make them more vulnerable to diseases such as brown jelly disease. 

And, if the water flow is too weak, algae, detritus, and other waste will settle on your coral. Think of Goldilocks, not too much, but also not too little, you want to hit the water flow speed just right!

3. Supply The Correct Lighting

Next, you should focus on the lighting. 

Hammer corals are highly dependent on lighting for the symbiotic algae (zooxanthellae) inside their tissues to perform photosynthesis. Photosynthesis provides your coral with its main source of food and nutrition to grow and thrive inside the aquarium. 

For optimal growth, LED or LED and T5 hybrid lighting fixtures are best. But do not worry if you are an old-school aquarist who uses metal halides, you can still grow hammer corals, but your hammer coral is likely to grow much slower, and you will also need to adjust the settings to meet their PAR requirements. 

For hammer corals to grow, they require a PAR range between 80 and 150, and a color spectrum of 10,000 Kelvin or slightly above. Most aquariums today focus on very blue LED lighting to show off their glowing corals. So, you probably want a full-color spectrum that is heavier towards the blue range, but also a spectrum that includes some reds, oranges, and yellows to enhance your hammer coral’s growth rate. 

4. Feed Them

Even though your hammer coral gets the majority of its nutrition from photosynthesis, this only accounts for around 75%. The remaining 25% comes from phytoplankton and additional nutrients and elements in the water. Therefore, feeding is necessary for your hammer coral to maintain a healthy growth rate. 

To promote healthy growth, you must pick out the best coral foods that will cover your hammer coral’s supplementation needs. As LPS corals like your hammer coral have large mouths, they can be fed pellet foods that contain plankton, mysis shrimp, brine shrimp, and amino acids. 

Coral pellets are our favorite for LPS corals, because they provide corals with condensed nutrients that can easily be target fed and they are formulated to encourage strong growth and vibrant colors. Pellet foods, like Coral Frenzy, are known to be “the ultimate coral food” for growing fat LPS corals. 

5. Supply Enough Nutrients

In addition to photosynthesis and feeding, your hammer coral also requires nutrients like nitrate and phosphate for optimal growth and coloration. 

I know what you are thinking… “Aren’t they the two water parameters I need to keep low?” 

Yes, you are correct, you do not want the nitrate levels to exceed 10 ppm, and as for phosphates, these should be no greater than 0.10 ppm. Maintaining these nutrient levels within the range without too many fluctuations and preventing them from hitting rock bottom or shooting through the surface, is crucial for your hammer coral’s growth rate. 

Excessive nutrients cause excessive algae growth, which can turn your hammer brown, negatively affecting its growth rate. On the other hand, insufficient nutrients can kill beneficial algae, causing your hammer coral to lose its mesmerizing color. 

To maintain healthy nitrate and phosphate levels inside your aquarium, remember to frequently test the water parameters and perform regular water changes.

6. Provide Plenty Of Elements

Elements are also important to maximize your hammer coral’s growth and build its calcium carbonate skeleton. Building the coral skeleton is the time-consuming part, which is why many hobbyists find their hammer coral either growing very slowly at the beginning or nothing at all. 

By maintaining consistent calcium, alkalinity, ad magnesium levels, your hammer coral should have no issues in growing and maintaining its beautiful colors and building its skeleton. I must emphasize the consistent part because, for example in aquariums, inadequate alkalinity is the fastest killer of corals. 

Successfully dosing your aquarium with these three essential elements, will determine if your hammer coral will take 2 months, or 2 years to double in size. 

The best advice I have is to get yourself a dosing pump. Not only do they automatically dose your aquarium water, but they control the amount that goes in, preventing overdosing. 


Keeping LPS corals like hammers can be challenging, and maximizing coral growth rates, is an even bigger challenge. Hammer corals are fairly unpredictable when it comes to their growth rate. While some hammers will grow a few heads within a couple of months, some hobbyists find that it can take years for their hammer coral to successfully reproduce. 

However, they are ways to promote and maximize your coral’s growth rate. Maintaining a stable environment of light, flow, food, nutrients, and elements, and minimizing aggression by allowing enough space between corals, will all contribute to how fast your hammer coral will grow. 

Remember that patience is key in coral husbandry, but trust me, it will be worth the wait!

  • Roy Lee

    I have an unhealthy obsession with reef keeping and maintaining successful tanks. If you haven't noticed from the website, I love everything related to saltwater tanks like coral, fish, and everything else in between.

1 thought on “Hammer Coral Growth Rate”

  1. I had the best Hammer coral growth when using Osram Compact lighting. That hammer coral did not stop growing and got huge.
    Fast forward today and ten years out if the hobby, I purchased a small frag three month ago for my new 75 gallon aquarium. I’m using high end LED lights and the Hammer is struggling to grow.


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