Over the years I have used both two-part dosing and calcium reactors for calcium and alkalinity supplementation. Two-part is good because it allows for precise dosing of each component. And it provides important major and minor trace elements for corals.

 

However, two-part can be expensive if you use pricey, ready-made solutions and have corals that require a lot calcium and alkalinity. With this new tank I decided to use a calcium reactor since I was planning to have a lot of SPS.

 

One drawback with a calcium reactor is that it will lower a tank’s pH. How does a reactor lower pH? Well, carbon dioxide is injected into the reactor to lower pH to help dissolve calcium-based media inside. This calcium-rich liquid or effluent is then dripped back into the tank.

Using Kalkwasser to Elevate pH

Nonetheless, there are some things you can do to elevate the pH coming out of a reactor. One is to use kalkwasser. Hydroxide ions in the kalkwasser use carbon dioxide to increase alkalinity and, as a result, removes excess C02 and increases pH.


Kalkwasser can be added by running RO/DI water via an auto top-off device through a reactor with kalkwasser. Some of these kalk reactors utilize stirrers on the bottom to mix and saturate the kalk. In the past I have used a reactor with a small external pump to mix the kalk.

 

Due to photosynthesis, the pH in a tank will drop at night when the tank lights are off so it is best to boost the pH during this time with kalk. I typically set my pump to run 4 times during the overnight hours for 15 minutes a pop to stir the kalk.




Another Way to Elevate pH

A second way to elevate pH is to have a second chamber on a calcium reactor to help absorb the excess carbon dioxide. I chose a brand-new model of calcium reactor manufactured by Reef Octopus and distributed by CoralVue. Both chambers on this Reef Octopus VarioS CR3000 reactor are 7 inches wide and nineteen inches tall.

 

REEF OCTOPUS VarioS CR3000 Dual 7inch Chamber Calcium Reactor

 

My tank is 225 gallons but the unit is actually rated for tanks up to 580 gallons. Yep, I plan to have a lot of SPS and have a heavy demand for calcium and alkalinity.

Key Features

In terms of the design, this unit has a couple of cool features. One is the built in pH probe holder. I really like this because it will allow me, via my GHL controller, to shut off the C02 if the pH inside the reactor gets too low. This will help me achieve my target calcium and alkalinity levels and prevent a ton of C02 being dumped into the tank if something goes wrong with my C02 regulator.

 

REEF OCTOPUS VarioS CR3000 Dual 7inch Chamber Calcium Reactor

 

Another great feature are the lids. They screw on very easily and do not have any of those annoying thumbscrews.

 

This reactor also comes with a VarioS 4 variable speed pump that maxes out at 40 watts. The pump re-circulates the water upwards in a reverse flow, which prevents the media from compacting down on the bottom of the chamber. This not only improves the efficiency of the reactor, but it makes it easier to clean when it is time to swap out the media.

 

REEF OCTOPUS VarioS CR3000 Dual 7inch Chamber Calcium Reactor

 

 

To regulate the flow of effluent this reactor does have a control valve, although I opted to pick up a Kamoer peristaltic dosing pump for extra precise dosing.

 

kamoer dosing pump

Final Thoughts

So far I am very impressed with this reactor. It is easy to use and has been a set it and forget it piece of equipment. My alkalinity has been rock solid and my corals seem to be pretty happy.

 

 

Shop GHL/Royal Exclusiv/Reef Octopus/Pax Bellum Equipment

 

 

If you would like some help with a new tank build, including help designing a custom aquarium, or help re-configuring your current setup then you can visit this page for more information. And if you are looking to add some equipment, I do sell GHL, Pax Bellum, Reef Octopus Calcium and Kalk Reactors and Royal Exclusiv products, including Dreamboxes, which is the equipment I use and recommend.

 

As for additional insights and information, please explore my many other reef tank and SPS related articles as well as my YouTube channel. For an even deeper dive into reef tank care you can check out my Reef Keeping Master Class. This online course is an immersive and one of a kind educational tool designed to help reef aquarium hobbyists build and maintain a beautiful SPS reef tank. The course is a series of video presentations with some supplemental video from my YouTube channel. There are also quizzes to help students retain and understand the information presented in the course.

 

Need some frags…..I can help with that as well 🙂 Please shop both my fresh cut and WYSIWYG frags to see what is available.

 

Happy reef keeping!