I’m here today to tell you about the UltraReef UCS 120 Calcium Reactor, recommended for tanks up to 130 gallons, and tested on my 100 gallon reef tank.

The reactor is equipped with a solid pump, the sicce Syncra 1.5, which I tested in the past and found to be a great product (the review).

The UCS 120 comes with all its necessary accessories, including a bubble counter and a probe holder. You only need to add a feed pump, which can be replaced with a deviation from your return pump, a method that I’ve been using for several years.

Since this is just the reactor, you also need a CO2 gas cylinder, a pressure reducer, and connecting pipes.

Technical Specs:

The reactor is aesthetically pleasing, constructed with a central acrylic column and a lathed base and the cap. The connecting pipes are made of grey PVC, and it is built and assembled entirely in Italy.

The screws used for this reactor are stainless steel AISI316, but they may eventually be made of titanium.

Working principles

The reactor is a classic cylinder, with an external air recycle system and an empty internal cylinder, ready to be filled with media. Water is pushed in by an external pump (not included), or by a deviation from the return pump, directly under the cover of the reactor. From here, water is sucked by the pump and mixed with CO2 as it’s pushed down to the base of the reactor where it is diffused through a perforated circular plate about 4.7 inches wide.

The sicce pump moves 0.3 gallons per hour and the head is 67 inches in our test.

Above is a close-up of the diffusion plate

Pictured below is the cover, which has the probe holder, water inlet and outlet, and the CO2 input from the bubble counter.

The construction, internal circulation, and concave structure of the top cover guarantees a complete CO2 recovery.

A non-return valve and a drain valve are included (the picture below shows where I replaced it with a different drain valve for greater accuracy)