Calcium Reactors: 7 Things You Should Know (For Beginners)

As a new reef keeper, you might be overwhelmed with tasks to do in maintaining a suitable tank for your coral collection.

And a calcium reactor is one of those devices that you are contemplating whether to get or not.

Well, you must first familiarize yourself with it before deciding.


Are Calcium Reactors Worth It?

Yes. Calcium reactors are worth it as they help in maintaining the required level of calcium and alkalinity in your aquarium and help with the tank’s maintenance.

You might always hear your co-coral enthusiasts talk about calcium reactors. They might be sharing the perks they enjoy as soon as they put a reactor in their aquarium.

If you are new to calcium reactors, one of your questions will be whether they are worth it or not since they are pretty expensive upon the initial setup.

If you will greatly consider the wellness of your marine inhabitants, then calcium reactors are, indeed, worth it as they regulate the level of calcium and alkalinity that your reefs need.

Calcium reactors help with the development and flourishment of your corals and other organisms that need calcium inside your tank.

These sets of equipment ensure a constant supply of calcium and other components to resemble the water type in the ocean which is the natural habitat of your corals.

Aside from the benefits to your corals, calcium reactors are also worthy as they will help you in the daily maintenance of your tank.

Once you have set up your calcium reactor based on your preference, you just need a quick check of the CO2 bubbles and the dripping of water every day, refill the CO2 occasionally and displace the calcium reactor media yearly.

Calcium reactors might be expensive, but they are simpler and more economical to maintain in the long run while you enjoy their efficient performance.

Are Calcium Reactors Necessary?

No. Calcium reactors are not necessary as their presence is essential only depending on the size of your tank and the numbers of your aquatic organisms in it.

As a beginner, you do not need a calcium reactor initially. You probably have a small aquarium with few corals as you just started your journey being a reef aficionado.

A little tank does not demand much calcium and alkalinity, so regular changing of water and adding calcium hydroxide powder, like Kalkwasser, will be sufficient to sustain your tank’s health.

However, as you add more corals, the demand inside your tank is increasing as well. Thus, some two-part solutions, like Two Little Fishies C-Balance, can be used in maintaining the calcium and alkalinity in your water.

If you will upgrade into a medium or large aquarium that you plan to fully stocked, then it is high time to get a calcium reactor to sustain the needs of your reefs. The simple maintenance that you are doing in your small tank is no longer sufficient in this new reef tank.

Should I Get A Calcium Reactor?

You should get a calcium reactor if you have a medium to large reef aquarium that is heavily stocked.

Not all aquariums need a calcium reactor. The small ones just require frequent changing of water, some calcium hydroxide powder, and a two-part solution.

You should get a calcium reactor once your reef tank is fully stocked already. A reactor is needed to sustain the higher demand of your corals for calcium.

If you have a massive reef, then it would be challenging to manually keep up with the consumption of calcium. It would be expensive to buy the supplies you need too.

With bigger tanks, you will need to increase your supply of calcium to make sure all your corals, regardless of their position in the aquarium, will be supplemented.

A calcium reactor is also more beneficial as the media that you dissolve is made of natural coral fossils. Thus, you are providing your corals the calcium and other minerals they need in the most natural way.

What Are The Best Calcium Reactor Media?

Made of natural minerals that can be used for typical calcium reactors and even as an addition to the tank’s substrate. It is also free from chloride and sulfate, has average particle size, and provides bounty calcium, carbonates, magnesium, potassium, and strontium.

ReBorn is made of fossil skeletons collected in the Western Pacific Ocean. Its size is suitable for any reactor allowing free flow of water and smooth dissemination of carbon dioxide. It also breaks down thoroughly so you will not encounter any mush.

Do You Need CO2 for a Calcium Reactor?

Yes. You need CO2 for calcium reactors as it is affecting the pH of the water which is responsible for dissolving the calcium reactor media.

CO2 or carbon dioxide is needed to maintain the appropriate pH of water in your aquarium. Proper pH is important to make sure your media will break down to effectively enrich the water.

So, what is this CO2 doing? With the addition of CO2, a weak acid is created that dissolves the media or the coral fossils.

It is decreasing the pH level of the water in the chamber, approximately by 6.5, which helps in dissolving the coral skeletons that leads to the creation of effluent, a fluid that is full of calcium. This effluent is expelled into the water tank to maintain calcium and alkalinity.

Injecting more CO2 will lower the pH which can melt the calcium reactor media (coral skeletons) adequately.

Meanwhile, less CO2 means that the pH will be too high which simply cannot dissolve the media.

Dosing Pump VS Calcium Reactor

Both dosing pump and calcium reactor are used to maintain calcium, alkalinity, and magnesium in your aquarium’s water.

Basically, a dosing pump is recommended to be utilized for smaller tanks that have fewer corals. On the contrary, a calcium reactor is commonly featured in medium to large tanks that are heavily loaded.

Dosing Pump Pros

One of the advantages of dosing is the lower cost for its initial setup. This is much affordable which is perfect for new coral keepers who are maintaining small tanks.

Also, a dosing pump has a simple setting that provides you a very convenient way for any adjustments you need. It has a compact size and features very precise information of how much liquid is added every 60 seconds.

You just need to set up your dosing pump, indicate your preferred dose, and just do some chemical refilling if needed – very simple!

Dosing Pump Cons

As for the drawbacks, dosing can be costly in the long run if you will upgrade your tank’s size and get more corals. You need to buy more dosing liquids as the demand for calcium, alkaline, and magnesium also intensifies.

Each supplement that you dosed in your tank requires a specific pump so you will probably end up having several pumps.

Likewise, the chemical refilling is usually causing a blockage in the outlets.

Calcium Reactor Pros

Calcium reactors have lots of benefits not just to your corals, rather to you as well.

For your corals, calcium reactors are offering a more resolute level of calcium and alkalinity as they are continuously running as well.

These reactors are highly beneficial as they are providing the corals the nutrients they need in a very natural way through the fossils of real corals.

They also require low maintenance which can save you money in the long term which is very ideal for big tanks with high calcium demand.

With calcium reactors, your tank keeping will be easier as once you properly set them up, you will just change the media and replenish the CO2 tank which can be typically done annually.

Calcium Reactor Cons

With advantages come shortcomings too and calcium reactors are not an exemption.

The first con of these reactors that commonly limit customers from buying is the higher initial setup which can be about $300.

Calcium reactors are also big and quite bulky which is not suitable if you have limited space. Most of their parts are movable as well so there is a high chance of leaking or tearing since you need to dismantle them if you need to replace or clean some parts.

Lastly, one of the major cons of reactors is the use of CO2 bottles. These are pressurized bottles that must be handled with caution as they can be dangerous if they will fall on the ground or break their regulators.

How Long Does Calcium Reactor Media Last?

A calcium reactor media typically lasts up to 12 months depending on your calcium reactor.

You should change your media before it gets completely empty in your reactor.

Some are replacing their media as early as 6 months. Commonly, experts are suggesting to change your media annually.

Calcium Reactors


Adams, J. (2021, April 21). 10 things to know about calcium reactors. Reef Builders | The Reef and Saltwater Aquarium Blog.

Huntington, S. (2008). A guide to using calcium reactors. Reefkeeping Blog.

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