Can You Have Too many Corals In A Saltwater Tank?

For anyone keeping a reef tank, you know how addictive adding new corals to the tank can be.

We all want to have colorful corals thriving in our tanks and it can be difficult to resist buying them. 

Unfortunately, there is a price to pay for having a tank stuffed full of corals. 

Yes, you can have too many corals in a saltwater tank. Keeping several corals that are jammed packed together will lead to many different problems including aggression and poor water quality.

Although it can look amazing, this can be a costly mistake that many hobbyists make.  

In this article, you will learn why you should not have too many corals in your saltwater tank. 


Problems with having too many corals

The biggest concerns with having too many corals in the same tank include:

  • Aggression
  • Water quality 
  • Less tank space
  • Algae outbreaks
  • Corals are not able to grow naturally
  • Corals not able to receive proper water flow and light

Read: Green Star Polyps care guide

Aggression concerns

Not all corals will get along together. Many of them need plenty of space between each other to prevent them from being stung. Corals can be very aggressive. 

Corals will always fight for real estate in the tank and although many corals will get along fine and can touch without issue, there are many that can’t.

Coral tentacles can extend and sting others in its area which can be deadly. Torch corals and Hammer corals are examples of this.


torch coral care guide


Corals can also release a chemical that is toxic to other corals around it. They can produce a toxic cloud around them killing other corals within reach.

Many soft corals like mushrooms have this ability. 


Water quality concerns

Having too many corals in your tank will definitely lead to poor water quality concerns. Anytime you add heavy levels of livestock into your tank, your bioload will increase. 

This bioload increase will cause water parameters to change. Nitrate, phosphate is going to increase.

Also having a lot of corals will cause a depletion of other important levels that corals need to stay healthy. 

Calcium, alkalinity, magnesium can be used up rapidly causing serious health concerns if not addressed. Having too many corals in your tank will require more maintenance on your part.

More water changes and dosing will be needed.  

Less tank space

More corals will equal less tank space. This will be a problem for fish as they won’t have the required amount of room to swim.

Also, less tank space means less room for the corals to grow and expand out. Aggression issues will result.

If you are running out of space in your tank, consider fragging your corals or upgrading to a larger tank.


Algae outbreaks

If your tank is heavily packed with corals, your water quality can suffer. Poor water quality will lead to algae outbreaks which can be difficult to recover from. 

If your tank is fairly new, you will notice diatom algae forming at higher rates if your tank is heavily stocked.

With high levels of phosphate, you might encounter green hair algae, cyanobacteria, and other nuisance algae that can be very hard to address if your tank is full of corals. 


Corals are not able to grow naturally

When corals don’t have enough space in the tank, they are not able to spread out and grow as they should.

This can cause many problems including stress, discoloration, aggression, and death of the coral.

It’s important to provide enough space in between each coral to allow them to act as they naturally would in the ocean. 


Corals are not able to receive as much light and flow

This is very common with tanks that are packed with too many corals. It’s easy for corals to block each other from the much-needed light and water movement.

Without this, corals will suffer and die. Depending on the placement of the corals in the tank, it can make a huge difference between blocking other corals or not.

It’s possible for a coral that needs plenty of light and water movement to be completely blocked by another coral preventing them from getting the nutrition they need. 

Check out: 7 Important Steps for dipping saltwater corals

Can you add too many corals at once?

It’s important that you only add corals to a saltwater tank that is fully cycled and healthy.

All water parameters need to be within limits and you should only add corals slowly over time. 

If you have a well-established tank, you can add multiple corals at the same time.

But there is a limit as you don’t want to increase the bioload too fast.

All animals in your tank will produce waste and this can lead to toxic levels of nitrate harming fish and other corals in the tank. 

It’s generally not a problem to add a few corals at the same time but avoid adding too many all at once. 


Can you have too much flow in a reef tank?

Another huge problem with having too many corals in your tank is it will be difficult to ensure the proper water flow rates for all the corals. 

It’s definitely possible to have too much flow in a reef tank.

Depending on where your corals are positioned and the types of corals in the tank, the right amount of flow can be difficult to attain. 

You might end up with certain corals getting too much flow and others not enough. Without proper space to move them around, this can be a problem. 

Also as mentioned, it’s possible for corals to block others from the water flow that they need. Water flow is crucial to a coral’s health and having too many corals in the tank will make it difficult. 



To answer the question, yes you can have too many corals in a reef tank. But depending on your tank size and types of corals, it’s possible to have many corals in the same tank without issues.

You need to plan ahead of time and keep in mind the problems that can arise if you pack your tank full of corals.