Toadstool Coral Not Opening – Should You Be Worried?

Among all other corals, toadstool leather coral is one of the easiest to look after. They are very friendly and survive for a long time in an optimal environment. 

So, what are the reasons behind your toadstool coral not opening?

First of all, toadstool coral not opening is a natural phenomenon. This is called shedding. By removing old skin, they can get rid of waste, algae, and debris.

That’s why you should always maintain a good balance of calcium and alkalinity. Also, good lighting and extra water flow can keep your coral healthy. 

Why Do Toadstool Corals Not Open Sometimes? 

Toadstool leather coral can live in your aquarium for years without raising any concerns. But they sometimes take too long to open.

Similarly, like Toadstool leather corals, Duncan corals also sometimes don’t open

Toadstool leather corals look like mushrooms but bigger. But when they mature, they can take on various beautiful shapes.

A fully grown toadstool coral is covered with polyps. Usually, the polyps are 1cm in length. 

However, they might sometimes get shrank, and their polyps don’t extend anymore. This phase is called shedding. This can happen multiple times in a coral’s lifespan. 

So, this phase can last up to 2-3weeks sometimes. It has multiple stages which can be easily identified. 

What Causes the Shedding?

If you might be asking yourself, the shedding is not a regenerative action. They simply do it to get rid of old skin. 

This helps them remove all waste and algae accumulated in a period. So, depending on the water’s purity, the shedding will trigger occasionally.

Also, having fish that spread sand everywhere can force your coral to shed more often. It can also be caused by too many algae in your mini ecosystem. 

5 Things To Do When Toadstool Coral Isn’t Opening

This entire process can take a week normally. But sometimes, it can take up to a month or so. This process can be caused/affected by bad lighting, water flow, and water quality. 

However, in a more optimal environment, your coral can shed faster. Here, we’ve discussed some tips that can help you build one. 

Bad Water Quality Can Trigger/Slow Down the Shedding 

Water conditions are always the first and foremost importance of reef keeping. Because the growth of your coral directly depends on it. 

Hence, if you can keep your water pristine and clean, your corals will grow nicely. 

Maintain a good water condition 

The proper water condition for the toadstool coral is given below 

  • Optimal Temperature: 75-80F
  • pH level: 8.1-8.8
  • Calcium level: 420-440 ppm
  • Alkalinity: 8-9.5 dkH
  • Magnesium Level: 1260-1350 ppm
  • Nitrates: Less than 10 ppm 
  • Phosphates: Less than 0.10 ppm 

Simply put, these will create the best environment for your toadstool coral.

However, we understand these may need elaborate explanations, and thus we have discussed them below. 

Improper Calcium and Alkalinity Levels Can Kill Your Coral

Among all other requirements, the balance of calcium and alkalinity matters the most. You can call them the keys to your coral’s survival. 

Keep Your Calcium and Alkalinity Balance in Check

For toadstool corals, we recommend maintaining a calcium level of 420-440ppm. The calcium is crucial for your toadstool coral and thus helps a lot in growth. 

The best way to maintain calcium levels is to use a good calcium test kit. To help you out, we have recommended our top picks below – 

Product 1
Product 2 

Unfortunately, in most cases, most people forget to maintain a proper alkaline level. However, in reality, you need to maintain a good balance between calcium and alkaline. 

The proper alkaline level in your water is 8-9.5 dKH. However, if you’re dosing carbon, keep it at 7-8 dKH. 

Lack of Magnesium Can Jeopardize Water Chemistry

After calcium and alkalinity, your focus should be on magnesium. It’s the third most plentiful molecule in seawater. 

Check on Magnesium Levels Regularly

When you add calcium to your reef tank, the alkalinity balance falls. That’s where magnesium comes into play. 

Most reef keepers often forget about keeping a good magnesium balance which can be frustrating.

Adding magnesium to your water allows you to add more calcium without ruining the alkalinity.

The optimal amount of magnesium for toadstool corals is 1260-1350 ppm. Although, it can be raised to 1400-1600 ppm if you have to fight algae outbreaks. 

However, you can also lower your magnesium level whenever you want to. 

Proper Lighting and Water Flow Can Speed up Shedding 

Like other corals, toadstool corals can grow faster under proper light and moderate water flow.

Also, their shedding process will be much faster if both of them are provided. 

Use Lights and Maintain Moderate Water Flow

The recommended lighting for toadstool leather coral is PAR 80-250. You can use any T5 lights, LED, or Metal Halides for them. 

All of them can grow corals properly under recommended PAR level. For the best colors, you can use a 14-20k color spectrum. 

As for waterflow, place your coral around two-thirds of the aquarium’s height. By doing this, you’re letting your coral have enough space to grow. 

Then make sure it receives a moderate amount of current. 

Excess Nitrates and Phosphates Can Cause An Algae Attack

Nitrates are solely responsible for the growth of algae or zooxanthellae. On the other hand, phosphates must be balanced and kept in check. 

Too many phosphates will help the algae growth, which then will force coral to shed. We already know that having too many algae slows down the shedding process. 

However, a lack of phosphates will cause starvation among corals.   

Change Water Time to Time 

The proper nitrates and phosphates are less than 10ppm and .10ppm, respectively. 

When your nitrates reach 10ppm, the water should be changed. As for phosphate, you can just change the phosphate media, and everything will be fine.

You can use a nitrate and phosphate test kit to keep track easily. 


Question: Why won’t my toadstool coral open? 

Answer: When some algae issues or fishes spread sand all over, your coral might shed. It develops a smooth, waxy surface and shrinks.

This helps the coral to get rid of any dirt and algae. Increasing water flow or having better water can make your coral shed faster. 

Question: Where do you place toadstool coral? 

Answer: It is advised to place toadstool coral at places that have access to moderate currents.

Please make sure the place is well-illuminated. These two together are very beneficial for your toadstool coral.  

Question: Is toadstool coral aggressive?

Answer: No. The toadstool leather coral is one of the most peaceful corals. They don’t have any sweeping tentacles or stinging cells.

However, they can produce more than 50 chemicals. Some of them can have a bad impact on smaller corals. 


So, that’s everything you’ve got to know on toadstool coral not opening. Hopefully, now you have what you were looking for.