As you can imagine, water chemistry is a huge deal in reef aquariums and there are many
methods to help maintain good water quality.
Because there are so many options it can be overwhelming on first glance, and it takes
some time to figure out what they all do and what makes sense for your home aquarium.
Let’s take a look at calcium reactors.
Right off the bat, it has a scary name.
Calcium reactor.
I need a reactor for my tank?
It’s actually not THAT complicated.
It is essentially just a chamber that recirculates water and slowly dissolves calcium carbonate
media.
By slowly reintroducing this water back into the aquarium, a calcium reactor helps maintain
calcium and alkalinity levels.
These two are major water chemistry parameters for stony corals and other tank inhabitants
such as clams.
The more stony corals in the reef, the higher their demand for calcium and alkalinity to
continue growth, especially fast growing stony corals such as Acropora.
The media is dissolved by slowly injecting carbon dioxide gas into the chamber.
Carbon dioxide when mixed into water converts to carbonic acid.
When the water inside the reactor becomes more acidic, the media starts to break down
and release calcium and alkalinity into the water making it bioavailable to the tank inhabitants.
Unfortunately, this process is also happening in the ocean as carbon dioxide levels rise.
If you have ever heard of ocean acidification, that’s what is being described.
The ocean itself is becoming more acidic and is preventing stony corals from growing or
worse dissolving their skeletons while the coral is alive.
It is part of the reason many of the reefs around the world are struggling or bleaching
out altogether.
The reason I like calcium reactors so much is they are fairly low maintenance once set
up and do a good job of maintaining calcium and alkalinity without the risk of crazy overdosing
if something goes wrong.
Usually if there is a malfunction, the reactor just stops working, it doesn’t dump a year’s
supply of additives into your tank.
I said these things were fairly simple, so let’s take a look at it piece by piece.
Let’s start with the chamber itself.
Usually it is a large acrylic tube with a large access port at the top to easily fill
and refill media.
The top has to be secured down to avoid leaks once the reactor is filled with water and
starts recirculating.
This one accomplishes this with a large orange O-ring and thumb screws around the entire
circumference of the top plate.
The media used is aragonite which is a great source for calcium carbonate.
I use a mix of aragonite and old coral skeletons that are laying around.
I could just throw them away, but in a MATRIX-like way, a calcium reactor can reuse them.
Once the reactor is filled, we set top top plate on and screw it down.
Make sure that there is no dust and debris on the O-ring or else the reactor might leak.
One quick way to tell if you have a good seal is the appearance of the o-ring itself.
It is squished down nicely and doesn’t appear to have any air gaps.
A calcium reactor requires two pumps, a feed pump and a recirculating pump.
Here is an example of a feed pump.
A small maxi jet 1200 or a cobalt does the trick.
It is important to get one strong enough to force water into the reactor while under a
little bit of back pressure because as the media dissolves, it turns a little slushy
and also the output of the reactor is going to be stopped down to a controlled drip.
The pump that does all the heavy lifting is the recirculating pump.
That’s this yellow guy here.
This particular reactor takes water from the top of the unit and sends it to the bottom
of the reactor.
The CO2 gets chopped up and diffuses back through the media in a constant loop.
The CO2 portion of the system requires a tank and regulator as well as a needle valve to
control the flow of gas to the calcium reactor.
It’s kind of a hidden cost to the reactor.
Often aquarists price out a calcium reactor but fail to account for the CO2 portion.
It’s usually a few hundred dollars for the tank and regulator depending on the size of
CO2 tank and the quality of the CO2 regulator and needle valve.
The regulators I’ve seen for the saltwater hobby are fairly inexpensive compared to the
very high quality ones used by the freshwater planted tank folks.
I’ve seen some CO2 setups for the freshwater folks into the 4-figures.
In any case, there is a connector for the CO2 here on the reactor that goes to a bubble
counter.
The bubble counter is a quick and easy visual reference for how much CO2 is going into the
reactor.
I shoot for about 1 bubble per second or less.
The real way to determine whether the reactor is working is to test the pH.
This particular reactor has a port on the lid for a pH probe so the acidity of the water
can be constantly monitored.
I shoot for a pH a little above 7.
In my experience when the pH is lower than 7 the reactor is a milkshake and if it is
up there around 8, there is probably no CO2 flow at all and either the needle valve needs
to be tweaked or the gas tank is empty.
Finally, the water leaves the reactor and heads back into the system through the effluent
line seen here.
It a little counter-intuitive to send back low pH water into the system, but this actually
helps keep boost the pH in the aquarium and add buffering stability.
When the reactors here are running well, our pH is a rock solid 8.3 and the tanks have
steady levels of both calcium and alkalinity.
I mentioned that calcium reactors are fairly low maintenance.
Our 10 lb CO2 tanks last about 3-4 months, and when they run out, it is a good time to
take the reactor apart and clean everything and top off the media.
So in summary, water chemistry is a really big topic, and there is a lot of different
ways to achieve good chemical balance for your corals.
Hopefully this video was helpful in understanding one of these technologies.
Thanks again for watching and don’t forget to like and subscribe.
Happy reefing everyone.