Why Is My Hammer Coral Not Opening-6 Reasons & Solution

Hammer Coral has gained popularity for easy growing. But sometimes owners get tense and ask, “Why is my Hammer Coral not opening?”

For Hammer Coral to bloom, it needs a favorable environment like balanced lighting, proper temperature, absence of ammonia, and a friendly companion. If your Coral is getting everything it requires, then it will bloom delightfully. While balancing the environment of Hammer Coral keep in mind that it is a Mediterranean creature. But excess of any of the required parameters will hurt the coral.

Hammer Coral is a very easy-going animal. But when there are sudden changes in its surroundings then it resists opening up as a defense mechanism. To get a more specific idea about the parameters this post will help you by addressing each problem. 

 Why Hammer Coral Is Not Opening- What to Do?

Hammer Coral Not Opening Troubleshooting Tips

1. New Environment

Hammer Coral is a very easy-going coral. But whenever they are added to a new environment they take some significant time to get used to the new environment. No matter how careful and precise you are, it is impossible to replicate two different tanks.

Therefore whenever you are trying to put a hammer coral in a new tank it takes time to adjust. It gets used to the lighting system, chemical formation, water density, and the overall environment. In adjusting periods by not opening up Hammer Coral creates a defensive shield. 

Once they get the assurance that the environment is safe for them, they open up automatically. Thus, if you are confident enough that you have been given a safe environment for Hammer Coral, stay tension free. 


The best solution to the new environmental problem is time. If you say that after placing your Hammer Coral in an environment where it is not opening up give it some time. The Coral can take about 2 to 3 weeks to open up. The time can vary depending on the care provided.

In this given time, ensure that the Coral is getting all the other elements it needs to survive and sustain. If every other factor is constant and provides proper nutrients you can see early bloom. It is safe to say that proper care is the ultimate requirement during the adjusting period for blooming the Hammer Coral.  

If the Coral doesn’t open up even in 3 to 4 weeks it is wise to consult an aquatic life expert. They can tell you the exact reason and what to do. 

2. Imbalanced Lighting

Whenever there are low or high lighting systems, Hammer Coral starts to misbehave. Hammer Coral is a photosynthetic animal. It uses Photosynthesis to produce energy for survival. It is one of the major survival requirements for Hammer Coral. 

Therefore when you put your Hammer Coral in low lighting it cannot perform photosynthesis properly. Thus it gets deprived of the main energy source to survive and does not open up as a defense mechanism.

If you want your Hammer Coral open in time, then provide proper lighting for photosynthesis. 

Hammer Coral needs good lighting doesn’t mean, you will need to provide heavy lighting to the coral. Especially if you are providing direct sunlight, it can raise the temperature too high for the Coral to survive.

It’s always wise to maintain a moderate lighting system for Hammer Coral. If sunlight is not working then take help from fluorescent light. 


For performing photosynthesis to create energy, Hammer Coral needs 80 to 120 PAR light. In the presence of the given amount of light, the Coral will bloom at its best. 

Any tremendous difference then the given light can cause harm and deficiency in the coral. Small variance is okay. But when the difference is higher than the required amount Hammer Coral tends to build a shield by closing up. 

Therefore even when every other factor is in the perfect amount, you will see that the Coral is slowly closing up. There are several PAR meters available in the market that can help to determine the PAR level. Every time you see any unusual behavior in Hammer Coral use the meter to check the level. (Our Pick: URCERI Light Meter)

3. Temperature

Hammer Coral needs moderate temperature to enhance its polyp and tentacles. The ideal temperature range is 78 degrees Fahrenheit to 79 degrees Fahrenheit. If the temperature range is anything lower than 76 degrees Fahrenheit Hammer Coral doesn’t act like its normal self. 

In the lower temperature, the coral doesn’t produce much energy through photosynthesis. To defend themselves from temperature change, especially if there is a sudden drop in temperature, they close up their blooming position.

If the temperature of the water is too high it can cook out the Hammer Coral. This means the Coral will get rigid with its polyp and tentacles. Any temperature higher than 83 degrees Fahrenheit is going to cook up the Coral which will ultimately damage the coral from the inside.

This special happens when you have placed the aquarium, where the Coral is, directly under the sunlight or have adjusted the temperature for any other aquatic life in the aquarium.


The best way to balance the temperature for the blooming of Hammer Coral is to add a thermometer to the aquarium. This way you can always keep track of the temperature and act accordingly. 

If the temperature is too low, you need to increase the use of a water heater for the aquarium. Aquarium heaters will always be at a specific temperature. On the other hand, if the temperature is too high you can put the aquarium in a shady place for a while. Also changing the water can help in lowering the temperature.

4. Presence of Ammonia

Ammonia is one of the elements that get into the aquarium as a byproduct of fertilizers and flakes of food used for animals in the aquarium. But unfortunately Hammer Coral has zero tolerance toward ammonia.

Even a small trace of Ammonium makes Hammer Coral sick. The Coral starts to show symptoms that are not well. The first symptom is closing up. If the coral has already bloomed it will close up in no time if it gets affected by Ammonia. 


If the dimming of Hammer Coral is caused by Ammonia it should be detected as soon as possible. You can buy a kit for Ammonia testing.

Any existence of ammonia then you will need to take care of it. Aquarium-friendly Ammonia remover is a great help in this case. They’re available in aquarium stores, for any medical store. Following the manual of the product, you see it properly. The process of using these products is very easy.

If you don’t have access to ammonia remover immediately, try to change at least 25% to 50% of the existing water in the aquarium. It is not a permanent solution but helps a lot in releasing the tension of Hammer Coral. 

As the ammonia was not inserted manually, always check the ammonia level in the water. All sorts of corals get affected up to some level by the presence of ammonia in the water. 

5. Companion

When you put a Hammer Coral into the aquarium it is not alone in the tank. There are several other animals and plants present in the aquarium along with the coral. 

These companions of the coral are not always friendly. There are some critters. These critters tend to nibble on the tentacles and polyps of the Hammer Coral. Therefore the Coral gets irritated. 

Sometimes the corals use their tentacles and polyps to defend themselves. But that’s not always the case. As a defense mechanism from animals like peppermint shrimps, Hammer Coral closes up. 


If every other factor of the aquarium is perfect for Hammer Coral, and it still doesn’t bloom, it is time to see if other animals in the aquarium are bothering the Coral. For this, you need to take a closer look at the aquarium.

The best time to observe is at night. During the night time use a fluorescent light to see if other small creatures are nibbling on the coral polyps. If this is the reason then you will need to get rid of those creatures or place the Hammer Coral into a different aquarium. 

It is always wise to do a background check on animals before putting them with Hammer Coral. Some of the creatures can damage the whole coral even if it tends to be ok.

6. Algae

Algae for Hammer Coral

Algae play an important role in the life of Coral. People often use them to give colors to different corals. Even Coral takes help from algae in the photosynthesis process. But as we can say excess of anything is not good.

If there is an excess build up of algae, Corals don’t bloom properly. This is especially true for Hammer Coral. In the presence of excess algae, the polyps and the tentacles get attached to each other and the rejects bloom. 


The presence of excess algae is noticeable not only on the Coral you will find it in the other parts of the aquarium. If you see that other animals in the aquarium are getting bothered by algae and the Coral is not blooming then it is time to remove the algae from the aquarium. 

To remove the algae from Hammer Coral take the Coral out of the aquarium and clean it with a brush. Make sure that the soft tissue of the Coral doesn’t get hurt or its tentacles don’t break.

Along with cleaning the Hammer Coral, take the necessary steps to get rid of the excess algae from the aquarium. During this process do not harm the aquatic animals.

How to Take Care of Hammer Coral

Taking care of Hammer Coral is not that difficult. Here are some tips to keep the Hammer Coral healthy and beautiful.

  1. Don’t change the water more than 50% at a time.
  2. If you are changing the parameters of water, do it gradually rather than suddenly.
  3. Maintain the level of parameters-
    • Salinity – 1.025
    • pH – 8.1-8.3
    • Water flow – Moderate flow
    • Calcium – 400-450 ppm
    • Alkalinity – 8-11 dkh
  4. Once a month take out the coral from the aquarium and gently clean it.


How Long Does It Take For Hammer Coral To Open?

As indicated by some aquarists’ insight, corals like Hammer Coral (Euphyllia Ancora) can require as long as three weeks to completely open. The significant thing is to not abandon legitimate consideration after you’ve seen nothing has happened seven days after the prologue to the tank.

Where Should Branching Hammer Coral Be Placed?

There ought to be some stream (low to medium), yet not an intimidating one. Setting the coral at medium tank level will work, as it will in general extend more there, in contrast to on substrate. Be certain that it’s put somewhere around 7 to 8 inches away from different corals as its arms (sweepers) will reach out up to 6, during the night.

Can Hammer Coral Recover?

The one in particular that made due however never truly recuperated was my sled coral. It lost the vast majority of its limbs and blanched, yet recovered a few tissues and a great deal of variety after around fourteen days. From that point forward there has been practically zero change.

How Big Can Hammer Coral Get?

In nature, Hammer Coral settlements can arrive at almost 3 feet in measurement! However, that will require numerous years and the biggest of aquariums to accomplish in bondage. More modest corals can be kept in aquariums of almost any size as they develop. Also, assuming your coral develops too enormous it very well may be parted into frags (erring on that later).

Why Is My Coral Closed Up?

A few corals will deliver bodily fluid into the water when they blow up. This bodily fluid can make different corals close up. Additionally, our hands are unquestionably filthy and shrouded in a wide range of oils that can make corals close up. I would allow it daily or two for whatever to advance out of your framework.

Read More

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Final Words

Hopefully, after today you won’t ask why my Hammer Coral is not opening. Every beautiful thing needs to be taken care of. Especially when you are taking them from nature and putting them in your habitat. In such a situation you will have to try at best to replicate the natural habitat of the Hammer Coral.  

When you take proper care of Hammer Coral it will let you enjoy its natural beauty. The spreading of tentacles and polys of Hammer Coral creates a soothing look in the aquarium. They get a rhythm with the flow of water.

Howard Parker

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