Back in 90’s, reef hobbyists realized that corals need constant levels of calcium and carbonate in order to thrive. Two factions emerged at that time. Reef chemisttry experts developed methods to add Ca/kH into the tank through pre-prepared solutions – the Balling method and Randy’s 2-part solution, in Europe and USA, respectively. On the other hand, at the same time Calcium reactors were having their debut on the market.
Ca reactors took advantage easily on this battle. They were appealing gadgets, with a very sophisticated look and they were also more expensive – “So they must work better than adding some kind of powder into water, right?” About 2-3 years ago dosing pump units started to appear in the market with attractive new features, such as multiple and individually controlled pumps and digital tuning.
Reef chemists had levelled their strength on this clash. A boom of reefers started using the Balling method or 2-part solution abandoning the use of Ca Reactors. These methods were presented as inexpensive, more user-friendly and very efficient.  And these points are absolutely true. This raises the questions:

Are Ca Reactors going to disappear? To be honest, I don’t think so. Neither Balling/2-part methods nor Ca reactors are  perfect systems to replace Ca/kH/Mg in our systems. There are pros and cons for both sides, which I’ll try to describe:

Balling/2-part solution

Pros
–    Initial investment is inexpensive compared to Ca reactors.
–    User-friendly. You just have to press a few buttons to make adjustments.
–    Very efficient – for example, if you aim for a kH 9, you can get it easily.

Cons
–    It’s more laborious and time consuming. You need to prepare the solutions and you need regular testing, even when you get the correct dosage.
–    If not aware, you can easily add Ca and kH in a non-balanced way, leading to a Ca/kH disequilibrium (which sometimes can be very hard to correct)

 Ca Reactors

Pros
–    On the long term is cheaper.
–    Is more suitable for larger systems, more than 200 gallon (750L)
–    Ca & kH are added on balanced way, according the media you use.

Cons
–    Initial investment – besides the reactor itself, you also have to add Co2 cylinders, pH probes/controllers, and CO2 regulators onto the total cost.
–    It can be difficult to regulate, especially in the beginning and if you aren’t an experienced reefer.
–    You may still have to boost the system with Mg solutions or buy Mg media.

These are only a few personal considerations and I would like to add that in the past 6 years I’ve been using 2-part solution and Balling light method. In my entire experience as reefkeeper I only used aCa reactors for 3 months and then I sold it – it didn’t suit me.

In conclusion, I think both methods are reliable but neither is perfect. In the end, your choice will depend more on your personal feeling and aquarium size. Like many things of this hobby there are several paths to success (look at the lighting example: Metal Halides vs. T5 vs. LED’s) and you will have to choose the one that suits you best.

Happy Reefing!

Photo: Pedro Conceição