How to Raise Phosphate in Reef Tank? [5 Ways]

Do you believe your reef tank might benefit from an increase in its phosphate levels? Everywhere I look, experts recommend reducing phosphate levels as they can be harmful to the tank.

However, there are situations where reducing it too much might require you to raise it again. It’s worth mentioning that I’ve personally experienced the need to raise phosphate levels in my aquarium, and many of my friends have come to me with similar issues.

In this session, I will provide suggestions on how you can determine if your reef tank needs an increase in phosphate levels and how to do it without making any mistakes.

5 Ways to Increase the Phosphate Level in Your Reef Tank

1. Adding Activated Charcoal- Slow but the Best Raising Implement

From the general point of view, I won’t recommend anyone to raise phosphate levels in the aquarium. This is because high phosphate can cause excessive algae growth, loss to the aquarium inhabitants as well as eutrophication which results in the death of fish.

But if you find that your phosphate level is too low and the rate is not enough for the inhabitants, you should take some steps to raise the phosphate level to a perfect balance. 

In this case, firstly you can use activated charcoal or carbon. Well, general thinking is established that charcoal cannot raise phosphate levels as it takes up the debris of the tank.

But, to be honest, I found it quite beneficial in my reef tank. Along with cleaning the pollutants of the water, activated charcoal percolates to a slight amount of phosphate. 

As a result, the phosphate level won’t rise a high amount in a single moment. It will increase gradually making your phosphate level balanced and perfect for the living of the fish. 

2. Adding Extra Fish Food- Fast Raising Treatment 

The third point will contain the method by which you will need to raise phosphate at a fast rate. If you are in a hurry, in this case, add extra fish food to your reef tank.

Here I want to mention two species of fish food which are Mysis shrimp and Nori. Among the other fish foods, they work skillfully. Also, other commercial fish foods serve better.

This is because dry fish food like pellets and flakes contain almost 1% phosphate or higher than that. As you won’t need to increase the phosphate level to an extreme level, these foods will work better.

3. Using A Phosphate Supplement- Chemical-Induced Treatment 

Next, I will suggest an easy term that you can use to raise phosphate in your tank without any hassle. Nowadays, every type of chemical is available in the market.

In the same way, you can also get phosphate-raising chemicals or supplements in your nearby aquarium shop or may take orders from online websites.

You can add different phosphate supplements to your reef tank easily by noticing the instructions labelled in those supplements by the manufacturers. 

But, one thing, you should be conscious and careful of the product that you are using. Also, you have to properly measure and mix the supplement to the reef tank as instructed. Otherwise, it will be problemautic for your fish.

4. Eliminating Phosphate Removal- Mechanical Treatment 

Meanwhile, I have mentioned three types of methods where you have to put any one of them in the tank for phosphate-raising purposes. But now, I can suggest one that is different from the above.

The fact is, you have to remove the phosphate cleaner from the reef tank. Let me make it clear. Most of the time, hobbyists use some phosphate removal methods in their reef tanks.

Like others, I also used to add those. But suddenly, when I felt that the phosphate level was declining too much, I decided to remove the phosphate remover from my tank. And, yeah! It worked amazingly. 

In this case, you don’t need to add any chemicals or fish food. You just have to pick up the phosphate remover and let your aquarium or tank seep phosphate from the water. 

5. Checking Water Sources- Apply the Basic Knowledge 

Unlike the others, my last point is going to be quite separate from others. It is not any type of treatment. Rather, you have to check the type of water or water quality of the reef tank.

Sometimes, hobbyists use highly purified water in their tank which is near to distilled water. This may help your fish to remain free from the attack of fungi, bacteria or other pathogens.

But, such water lacks different types of nutrient materials including phosphate. If your tank is also passing through the same water, then try to change it. Use such types of water that are purified but not over-purified.

The tap water may contain phosphate levels properly. So try to use this if your phosphate level has declined much. After a certain and balanced level, you may add a purifier to keep the water perfect. 

Symptoms That Indicate Your Reef Tank Needs Raising Phosphates

Several symptoms can make you sure about the fact that your reef tank water needs to increase its phosphate percentage.

Improper Coral Growth

Coral needs phosphate for perfect growth. If the growth is slow, then it might be due to the low amount of phosphate.

Algae Growth

Though high phosphate also indicates algae growth, sometimes algae outbreaks can happen due to low phosphate.

Decreased water quality

Due to the absence of phosphate, nitrate and nitrite cycle may be induced, which decreases the water quality.

Bleached coral

Coral gets weaker over time if you can’t support them with enough phosphate level.

Why Do Phosphate Level Decrease in a Reef Tank? 

Several reasons may be responsible for decreasing the phosphate level in a reef tank. Check the below points to match with your reef tank if you have any-

Algae growth

A dense layer of algae can consume a high amount of phosphate that may sometimes become threatening to your reef tank.

Aquarium Substrates

Substrates containing iron or granular ferric oxide and other rocks may cause significant degradation in phosphate levels.

Phosphate remover

Phosphate removers are generally added to the water to remove high amounts of phosphates. But sometimes it may decrease much.

Biological uptake

Corals, microalgae and other organisms can go through different metabolic activities using phosphate causing much degradation of it.


High levels of the filtration system may also cause declining phosphate levels.

Water changes

Regular water-changing processes can cause the dilution of phosphates that lower the ultimate phosphate level.

Why Should I Maintain a Balanced Phosphate Level in the Reef Tank?

It is sad to say but I have met with some hobbyists who don’t remain bothered about the phosphate level in the reef tank at all. They neglect the phosphate range completely which causes different issues with the fish.

That’s why I think I should supply my observation about the importance of a balanced phosphate level so that you may become careful about them.

First of all, phosphates are needed for algae control. Excessive phosphate levels will cause a dense layer of algae. Consequently, the algae will create a barrier to receiving light from the submerged plants.

The plants along with algae will go through aerobic and anaerobic degradation caused by bacteria and will result in suffocating conditions for the fish by decomposing. 

If you don’t keep the phosphate at a balanced level, it will lead to the death of the fish over time. Also, the corals will be degraded by high amounts of phosphate level.

Again, elevated phosphate level hinders the calcification process of fish. In this way, they can perfectly form their protection shell in the high phosphate water.

On the other hand, low amounts of phosphate will make the fish sick. Fish and other aquatic inhabitants need phosphate to complete their life cycle and nutrients requirement. 

In the absence of enough phosphate, fish will get their needed condition or food to breed and continue their development cycle and will face a stressed condition. 

Precautions You Should Take in Raising Phosphate

As I said before, excessive phosphate level is harmful to the aquarium ecology along with the inhabitants. Too much phosphate can destroy your beautiful underwater scenery. 

That’s why before taking measures to raise phosphate, you should measure the amount of phosphate present in the aquarium water. If the measurement is below the ideal level, only then add other materials.

Also, after raising phosphate, you should monitor the phosphate level in the aquarium properly so that it cannot raise too much that crosses the extreme limit. 

Ideal Phosphate Level 

You know how important it is to maintain the perfect balance of phosphate in a reef tank! But to ensure the ratio, you have to know the optimum measurement of the ideal phosphate level in different types of aquariums. 

Hence, check the below table-

Water tankIdeal phosphate level  
Reef tank0.03-0.08 ppm 
Saltwater aquarium Less than 0.05 ppm
Freshwater aquarium Below 1.0 ppm 
Brackish aquarium 0.5 to 1.5 ppm 
Planted aquarium 1 to 2 ppm 
Nano aquarium0.03 ppm 
Coldwater aquarium 0.5 to 1 ppm

May I Need to Decrease the Phosphate Level Again?

Well, the answer to this question varies from person to person. It will depend on your techniques of aquarium care as well as accurate maintenance procedures.

As I observed in my reef tank, dead reef rock like tufa rock or crushed coral substrates, decaying organic matter, low water quality and overfeeding can increase the phosphate level much.

In this case, if you notice that the phosphate level is enhanced to an extreme level, you should take the necessary steps to reduce the phosphate level in your reef tank.

But don’t worry! You will find the procedure for reducing phosphate levels on my website. Following those techniques you can easily balance the phosphate level again.


How long does it take to raise the phosphate level in the reef tank?

Generally, it may take 4-6 days. But the time will depend on the method that you are using for raising the phosphate level. You can check from the main body which is the fastest way of it.

Can adding more fish increase the phosphate level?

Yeah! If you add more fish to your reef tank, they will create more debris and thus the phosphate level will increase much more than before. But I won’t suggest this method as you have to again take measures to decrease phosphate as the fish will continue producing facets. 

What Amount Should I Aim to Keep for Phosphate Level in My Tank?

It’s 0.05 ppm. Though the ideal phosphate level in a reef tank ranges from 0.03-0.08. But if you can put it fixed at 0.05, it will be in the best condition for the fish and other inhabitants. 

Final Words

Finally, I have reached the final point of my discussion. You should always keep in mind that maintaining stable water conditions is undoubtedly significant for your fish and other aquatic inhabitants. 

And, it is worth mentioning that, balancing phosphate level is one of that. You have to be conscious to observe the phosphate level and it needs regular checking.

If you are not sure about how to manage the reef tank’s water elements, you can consult with me via social media or consult with an aquarium expert for guidance. But don’t do anything without being sure.

Howard Parker

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