Flower Pot Coral Not Opening [4 Reasons & Fixing Guide]

Flowerpot corals are definitely the true show-stealer. They are also known as Goniopora and come in a variety of vibrant colors. Especially when they are open the corals resemble flowers! No wonder why every hobbyist craves them.

Unfortunately, flowerpot corals are a bit sensitive. Keeping them alive is not everyone’s cup of tea. Hence, often the question is asked, why my flower pot coral is not opening?

It happens when the coral starts to reduce in size and opens only sometimes. And at a point, the flowerpot coral becomes entirely closed. Hence, the owners become sick-worried if the coral will ever open again!

Well, there can be several reasons for the flowerpot coral not opening. However, the most probable reason is changing water. Water quality and pH affect a lot to the flowerpot corals. Moreover, inadequate lighting and inappropriate placements or adjustments can also occur the problem.

Since you have already decided to know it all from us, bear with us till the end!

4 Reasons for Flower Pot Coral Not Opening -Solution

Flower Pot Coral Non-Opening Causes

1. Water Quality and Parameters

Coral reefs require quality water for their healthy growth. Hence, it is the most important factor that affects the flowerpot coral. Let’s talk about the parameters of water quality that may be affecting the opening of flowerpot corals.

Presence of Alkaline, Calcium, and Magnesium

There should be a balanced and stable presence of calcium, magnesium, and alkalinity in the water where the corals are kept. These elements help in keeping the corals healthy. Hence, any interruption to the stability can affect the corals.

Even this situation is responsible for killing multiple corals at the same time. You need to ensure all the three elements in the tank water for the sake of your pretty flowerpot corals.

However, among these elements, alkalinity plays the most significant role. It maintains the pH of water. Moreover, it helps in generating carbonate and bicarbonate. These elements work as building blocks of corals. Hence, you get to see healthy corals.

Nonetheless, to maintain healthiness, consistency in alkalinity level is a must. So, if your tank water lacks alkalinity, calcium, and magnesium then it will create an adverse environment for the corals.

For example, it will slow down the coral growth or fade away the beautiful color of the corals. Showing these symptoms consequently, the corals become retracted or closed.

However, you need to also know that, excess of these elements along with precipitation can cause coral damage. This damage can also induce destroy of equipment in the aquarium. So, you need solutions.

Control Measure

  • To obtain the right measurement of alkalinity, frequently check it with the help of an alkalinity meter. You need to keep the alkaline value between 8 to 12 dKH (our pick: VIVOSUN Digital PH Meter for Water)
  • Moreover, the device also helps in measuring the amount of calcium and magnesium.
  • Always adjust the pH of the aquarium. It ensures a healthy environment for the flowerpot corals.
  • Also, go for a water change every day. A change of 20 to 25% will work properly.
  • Ensure sufficient calcium and magnesium elements in the water for proper growth and calcification of your flowerpot corals.

For your information, if the water has excess alkaline then you can amend it by mixing salt along with 8 or lower dKH.

Other Nutrients

Along with calcium and magnesium, corals also require nitrates and phosphates. These nutrients help keep up with the reefs. Without these nutrients, the flowerpot corals will stress out and in the end stop opening.

Control Measure

  • Ensure around 10 to 20 ppm nitrate elements are in the tank water.
  • In the case of phosphate, ensure about 0.05ppm phosphates for the healthy growth of flowerpot corals.


Nonetheless, the first and foremost thing to check in your tank water is its salinity. Salinity plays a great role in the opening of flowerpot corals. If the tank water is going through salinity changes, it might interrupt the adaption of the corals.

For your information, corals do not have an awesome osmoregulation system. In fact, the system is quite poor. That is why their adaptation process is also slow and requires a consistent environment.

So, excessive salinity is definitely going to harm your beautiful corals. Their structure reduces due to excessive salinity. This unfavorable modification later does not allow the flowerpot corals to open.

Control Measure

  • It is necessary to keep the salinity around 35 parts per thousand if you have placed the corals in a reef tank. So, check frequently if your coral reef tank obtains this salinity.
  • Also, maintain the consistency of the salinity. There should not be any abrupt change in the salinity of tank water.
  • You can also use a refractometer to keep inspecting the salinity level. The device provides an accurate determination of the salt content in tank water. (Our pick: Aquarium Salinity Refractometer)
  • Again, to control excessive salinity you can also exchange the saltwater with RO/DI fresh water. It will help to decrease the level of salinity.  

So, you can already predict how important it is to keep the salinity at the required level for flowerpot corals.

2. Adaptation and Placement

These two are also crucial reasons for most flowerpot corals not opening anymore. Most corals require a great deal of time for their adjustment to the tank water. It is because the tank conditions provide an entirely new environment for them.

So, it is important to ensure a proper and stable environment. Therefore, this reason practically depends on water parameters as well.

Again, the proper opening of flowerpot corals also depends on their proper placement. They should not be placed somewhere the water flow is too strong. In this situation, corals struggle a lot to open.

Control Measure

  • You need to ensure the required flow of water in the reef tank. It helps in the healthy adaptation of flowerpot corals.
  • Place your flowerpot corals in areas where the water has a medium flow.
  • Again, make an appropriate sand bed for keeping your corals.
  • Make sure, the flowerpot corals are getting enough water flow. But again, ensure that the flow is not direct.
  • Moreover, the water flow should not be short-ranged.

3. Lighting

Lighting for Flower Pot Coral

Lighting is a great factor when you add flowerpot corals to your reef tank. Corals are supposed to be exposed to a certain amount of light. Though they can adapt to a vast range of light too much exposure to lights will harm corals.

They cannot tolerate too bright lights since it creates excess hotness. Even, excess light might lead to unexpected shrinkage of corals. Moreover, the flowerpot corals might lose their polyps because of the active radiation. As a result, they may die within some days.

Then again, insufficient light also affects the flowerpot corals. It makes the corals discomfort and later they end up being perished. Even insufficient light makes corals turn brown while they grasp for lighting. It makes them stretched to some extent as well.

Control Measure

  • You need to know what PAR your flowerpot corals require. Get them the right ones and then place them. Mostly, flowerpot corals desire lower PAR.
  • To make sure your corals are getting the right amount of light, you can place them in the bottom or middle of the aquarium.
  • Again, provide low to moderate brightness to have healthy flowerpot corals.

4. Feeding and Care

Last but not least, feeding and care! Be it fish or corals, all the elements in a reef aquarium require proper care and feeding. This is an undeniable factor that also affects the opening of flowerpot corals.

Many hobbyists out there still think their corals do not need food. But this wrong knowledge is killing your corals. To speak fact, corals need frequent feeding. However poor feeding lowers the water quality and parameters.

Again, care is also required for the healthy thriving of corals. Poor caring also leads to poor water quality. You have to make sure you do not pollute the water environment. Any toxins or impurities in the water can affect the opening of corals.

Control Measure

  • Do not dip your hands when you have oils or lotions on them. Even soap can pollute the water of the reef tank.
  • Again, do not use aerosols near your aquarium. They add pollutants to the water.
  • Change the carbon if you inspect any toxins or impurities in the water.
  • If nothing works, change the water by almost 30% every day.
  • Again, if you meet any accidental and hazardous contamination then change the water by 50 to 90%.

Nonetheless, after the water change, make sure the water in the tank is evenly heated and blended.


How long do flowerpot corals take to settle?

The time actually depends on the tank conditions and its environment. If your corals get quality water then it will take about two days to open. For their full extension, they might take one or two weeks. However, a healthy specimen can settle anyhow even in lower tank conditions.

How long a flowerpot coral can remain shut?

Your corals might survive without light for about two or three days. But without water movement, they are not going to survive and may shut forever.

How do I take care of my flowerpot corals?

Just ensure moderate water flow along with moderate lighting in the reef tank where you have placed corals. Also, add all required nutrient elements including calcium, magnesium, alkalinity, and all. Again, make sure that the water is always free from toxins and impurities.

Is my flowerpot coral dying?

Flowerpot corals are easy to keep. They like to fall people in a hit-or-miss situation. However, if the corals have managed to survive for months in your aquarium, then they might not die that easily. But once the corals start to lose their tissues, they will die eventually. And it is quite tough to protect a dying coral.  

Final Words

It is true that most hobbyists go through horrible experiences of their Flowerpot corals not opening. Yet, you should not be discouraged since there are still several chances of saving them and making them open.

Their beauty and presence are worth every difficulty and challenge. These flowerpot corals are the ultimate slayers of your reef tank. Thus, once you get these rare pieces you should not miss out on the chances of saving them in your tank.

Take help from our solutions and let us know if you are helped enough through your feedback!

Howard Parker

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