Calcium reactor setup - The easy way for your reef aquarium - Reef FAQs

June 3rd, 2019
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Calcium reactors and the word “easy” in the same sentence is sort of an oxymoron because reactors get a bad rap for being difficult. The facts are, once you understand the concept it really is not all that hard. Our mission here is to share the easiest approach to calcium reactor setup that an average reefer can do with readily available equipment.


A calcium reactor uses carbon dioxide to melt old coral skeleton and enrich the tank water with calcium and alkalinity. Presumably, in the same ratio that the new coral skeleton will use it. In addition, other elements bound up in the coral skeleton, such as strontium, are also added in the process.


Vertex Calcium Reactor Setup


Calcium reactors are often presented as these complex devices that require all sorts of tuning but that is nonsense. They can look intimidating just because of all the plumbing, chambers and tubing but operationally they are quite simple. All you need to do is set it up to dose a consistent strength solution of calcium and alkalinity and then adjust how much you dose each day based on your tank’s demand.


Before reading further, it is important to familiarize yourself with the basic concept and we have some excellent videos about calcium reactors so here is a round up of videos to get you started.



pH Controller setpoint 6.5


Establishing a consistent effluent starts with a stable pH

First, you need to create a consistent effluent solution 24 hours a day, 7 days a week. The effluent solution being dosed into your tank should always contain the same concentration of dissolved calcium and alkalinity.


A steady pH inside the reactor is the ticket and is what maintains a stable strength solution. The exact concentration may vary a bit with different media types and reactor designs, regardless they all can produce a consistent solution.


During one of our BRStv Investigates videos we demonstrated a stable concentration at various pH setpoints using a Vertex RX-C 6D Calcium Reactor and Two Little Fishies Reborn Calcium Reactor Media.


BRStv Investigates Test Results


The results from our experiment above show that the pH setpoint negotiates the strength and we covered the entire pH range that most reefers would keep.


The pH setpoint of 6.5 is best and will be the safest setpoint to produce the most concentrated solution. We recommend the more concentrated solution because you don’t have to dose as much which means the feed pump will last longer and operate with less noise.


To further substantiate this, we also have a Reef FAQ video planned to show how dosing half as much of the lower 6.5 solution actually results in a higher pH in the reef tank as opposed to dosing twice as much of a higher 6.8 solution. Something we think a lot of calcium reactor users will find interesting.


pH Controller Options


Using a pH controller for CO2 injection

To maintain the stable 6.5 pH inside your reactor, a pH controller is employed to open and close an electric solenoid on your regulator. This will only allow the necessary CO2 to maintain the desired pH of 6.5, no more and no less.


Neptune Systems Apex Base Unit


Many reefers will use this as a good excuse to pick up an aquarium controller like the Neptune Systems Apex. The full Apex has two BNC ports for probe connection so you can monitor both the pH inside the reactor and in your display tank with the use of two pH probes.


Neptune Systems Apex EL Base Unit


The entry level Apex EL only has one BNC probe port which will suffice to control pH inside the reactor. You could then upgrade with an additional PM1 module to add the second pH probe if you decide you need it down the road.


Milwaukee pH Controller Kit


You can also get stand alone controller like the Milwaukee pH controller which only costs about $130 at this point in time. For those who are not tech-savvy, setting the pH on a simple stand alone controller is as simple as turning a knob. They are not as precise but the affordability and ease of use make these pH controllers an attractive option.


In either case, set the controller to maintain a pH of 6.5 inside the reactor and you will now have a stable concentration of calcium and alkalinity in your effluent solution.


Bubble Counter


As a precaution, it is wise to then tune your regulator output to a bubble rate that matches your goal of 6.5. Basically just tune the needle valve down to a point at which the solenoid is open a majority of the time. Doing so will provide some back-up redundancy in case the controller or probe were to ever fail.


Calcium Reactor Effluent


Adjust the effluent to meet your demand

Now that you have created a consistent effluent solution, you next need to adjust how much is going into your tank in order to meet your demand for major elements.


For example, if you start at the rate of 10 mL per minute and the tested levels of calcium and alkalinity are indicating a drop, turn up the flow to 15mL per minute and test again. Repeat the process in small increments until you are able to maintain your desired levels. Not much different than two part solutions most of us have used at one point and adjustments should be in small increments no less than 24-48 hours apart.


Reef Calculator Screenshot


In fact, just like two part there are easy to use calculators like Jdieck’s Calcium Reactor Set Up. Just enter a few fields and it tells you the exact flow rate to use.


The reefing community classically believed that turning up the flow rate of reactor would decrease contact time and because of that decrease the concentration of calcium and alkalinity in the reactor. Turns out that while that is somewhat true, it’s just not something most reefers should be concerned with because the drop in concentration is minimal.


BRStv Investigates Test Results


BRStv Investigates researched the topic and found even after cranking up the flow from 5 mL/min. to 100 mL/min. the concentration only dropped by about 15%. Rather than get lost in that science, it is far easier to test your tank and just dose a bit more if needed.


Vertex Needle Valve on Calcium Reactor


To control the flow rate there are two options. The less expensive option of using a valve works, but will become clogged over time resulting in more work to keep it clean and maintaining the consistent effluent drip you need.


Kamoer FX-STP Continuous Duty Dosing Pump


The best and of course more expensive option is using a continuous duty dosing pump. The FX-STP from Kamoer is the best option we carry and has really been a game changer for calcium reactor users.


“Continuous Duty” is the key word here; all of the other dosing pumps in the reefing hobby are rated to only be on minutes to hours a day. With the Kamoer pump, not only can it be run 24/7 but adjusting the flow is as simple as turning a knob. It is accurate, calibratable and critical components are completely replaceable.


In terms of dialing it in, if you need more calcium and alkalinity simply increase the flow rate, turn it down for less.


Related Content _______________________________________________________

Watch Video: Calcium Reactor Tuning with a Reef Tank Calculator

View Playlist: All Calcium Reactor videos

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