By Bob Goemans
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Mini-cal Calcium Reactor

Manufactured by: Marine Technical Concepts

A product review by Bob Goemans

Mini-Cal Calcium Reactor:

(Written in 2003)

As for calcium reactors in general, if you maintain a reef aquarium and don't have a calcium reactor you're missing out on an easy way to maintain a very stable environment. When a reactor is used it ends having to prepare and add Kalkwasser and/or dosing other type calcium and buffer additives. Imagine not adding either or most other additives. Many of those who still use these additives don't realize they are fighting the calcium and buffer war or simply adding unneeded constituents to the bulk water. They may add calcium one day and buffer the next only to find that the following day calcium level is again low. Then they add more calcium and find the next day the buffer is again low. Not only are they wasting money, they are stressing the inhabitants in their aquarium and may be skewing the transmission of light intensity and spectrum through the water.

Imagine having a very stable reef aquarium environment where, without adding any additives, calcium level remains in the low 400's, and alkalinity can remain between 10 to 14 dKH! Imagine your supply of additives reduced to only iodine! Well, that is very possible if you have a calcium reactor connected to your aquarium.

There's not many aquarists who are not familiar with the now famous Pro-Cal Calcium Reactor that Marine Technical Concepts began producing about four years ago. It had two 19 inch tall clear acrylic cylinders mounted on a base plate that had a footprint of 13 x 15 inches. One of its cylinders was equipped with a pressure gauge, a prefilter, and bubble counter for viewing carbon dioxide flow. A Little Giant Model 2 MDQ-SC was used as its circulation pump. Even though it was a little pricey many knowledgeable hobbyists and I considered it the best available.

Well, there's been a lot of calcium laden water flowing under the bridge so to speak for the last few years as the competition has tried to produce less expensive units. There's no doubt the competition was successful in producing less expensive reactors, but matching the quality and capability of the Pro-Cal has proved to be something like shooting at a moving target - a seemingly illusive and difficult task.

Yet, competition is healthy and has caused Marine Technical Concepts to look for a way to duplicate the quality and capability of the Pro-Cal in a smaller unit. Not an easy task and one which caused many sleepless nights as I understand it from the Wojcik brothers, Leo and Jeff.

First, some of the frills had to go such as the high quality calibrated glass flow meter (which is still available as an optional item), and the separate water inlet filter. Also, it was decided that a setup and maintenance video was no longer needed. A less expensive outflow valve was substituted for the Pro-Cal's exceptionally high quality needle valve. This, by the way, is also available as an optional item on the Mini-Cal and in my opinion should be considered a worthwhile investment. The entire unit was downsized to a base plate that is about 10 x 10 inches with its two cylinders now having an overall height of 17 inches. Since the new model was smaller, a smaller pump, a Mag 3, was used. The twin-tower Mini-Cal was born and at about half the cost of its bigger brother.

A pre-production model was sent to me for testing, which needed some serious rework on my part to get it ready for testing. The unit arrived with two stress cracks in the main cylinder at its lower fitting. I stopped drilled the cracks and sealed the area with special acrylic cement. I then noticed the flow control valve was missing from the second cylinder. I called Jeff and he sent one out in the next day's mail.

As things go, I just received a sample of a new calcium reactor media from CaribSea(3) called ARM (Aragonite Reactor Media). If there is a perfect media for calcium reactors, this has got to be it! According to CaribSea it contains the lowest percentage phosphate and silica when compared to other calcium reactor media's and it contains the highest concentration of Halimeda incrassata, an aragonite so pure it has been used as a laboratory standard. In fact, this media is so soluble that as much as half the normal amount carbon dioxide is needed for dissolving it, which was evident when I completed testing the Mini-Cal.

It took almost one full jar of ARM to fill the Mini-Cal's two cylinders, called the Reactor Tube and Post Reactor Tube. The cylinders were then filled with some freshly prepared seawater and their top covers were secured with their white nylon thumbscrews. The supplied sump bracket, which holds the blue suction/siphon tubing and the green reactor effluent return tubing, were attached to the side of the aquarium. The suction line was adjusted so that it extended down into the aquarium water. The output line was adjusted so that its height was slightly above the highest water level in the aquarium. The bubble counter, which is attached to the top of the Reactor Tube/Cylinder was filled with freshwater. The carbon dioxide equipment was hooked up; the outflow valve on the Post Reactor Tube was opened; and, the AC cord from the units Mag 3 water pump was plugged in. Once all the air was purged out of the cylinders the outflow valve was slowly closed so the effluent drip rate was about 110 drops per minute. For more precise drip control I highly recommend getting the optional needle valve as mentioned above. The carbon dioxide was turned on and set at 30 bubbles a minute, which is half the rate as recommended for the Pro-Cal.

The following day the effluent from the reactor had an alkalinity of 7 meq/l. That's twice the recommended level for most reef aquariums. However, the range where reactor effluent should be is 3 to 5 times the desired alkalinity in the aquarium. Reef aquariums should have 10 to 12 dKH or 3.5 to 4 meq/l. Keep in mind one meq/l equals 2.8 dKH. The unit was located on the floor about ten feet from the aquarium. The Mag 3 pump was strong enough to send the unit's effluent to a height that exceeded 6 feet, and that was plenty sufficient to get it over the side of the aquarium.

Over the next couple of weeks the effluent was tested every few days. The flow of carbon dioxide remained at 30 bubbles per minute, as did the drip rate at 110 drops. The unit's effluent alkalinity increased to 10 meq/l. On the third week the carbon dioxide was increased to 60 bubbles as a test and by the next day the effluent's alkalinity was 16 meq/l, far too high! The flow of carbon dioxide was cut back to about 30 to 35 bubbles and effluent alkalinity remains steady at about 14 meq/l. Of course, if effluent drip rate is slowed, its alkalinity level will climb, however, with a 125 gallon complex reef system, a flow rate of about 110 drops per minute suffices in my system.

The circulation pump, besides drawing water from the aquarium or sump and returning calcium-laden water back to the aquarium, also circulates water through both cylinders. This is where its bigger brother the Pro-Cal and the Mini-Cal differ from other calcium reactors. Calcium laden and pH reduced water flows from the first Reactor Tube to a separate cylinder called the Post Reactor Tube. It slowly passes through this second aragonite filled cylinder raising its pH and "dissipating" most or all of any remaining carbon dioxide. In fact, prior to the ARM product more carbon dioxide was needed because other media was not as soluble as the ARM product. More carbon dioxide usage resulted in a lower pH effluent and resulted in aquariums with a slightly lower pH. Now, with ARM, less carbon dioxide is needed to dissolve the media resulting in an effluent with a slightly higher pH and a saving in carbon dioxide usage/refills. Yet, because it does dissolve more easily, reactor servicing will be more frequent. But that's actually a plus, not a negative!

All in all this budget minded Mini-Cal, which comes with three pages of installation and operating guidelines, is just as good as its bigger brother for most systems. It may not be as fancy as its bigger brother, yet its an extremely capable and quality product.

As with all the equipment from Marine Technical Concepts, this device is extremely well made and satisfaction is guaranteed. And, if you need to talk to either Leo or his brother Jeff, they "will" personally take your calls and spend the necessary time to answer questions and insure that you will be a happy and satisfied customer.

Before I close on the review of the Mini-Cal, I want to note that the unit does not come with a carbon dioxide bottle or regulator. These items are something you'll need to supply. I recommend purchasing a carbon dioxide bottle from your local welding supply company. Bottles come in different size, i.e., 5, 10, 15, 20 pound and larger. Since you're going to refill the bottle at some point in time, a local welding company may not want to refill a bottle they have no safety record on. It would also be more practical to purchase a regulator that is equipped with a "solenoid." For those of you that are not familiar with that term it is simply an electrical device that will shut off the gas flow when there is a power failure. If you purchase a regulator without a solenoid, carbon dioxide will continue to flow during a power outage. If this occurs, the water in both cylinders will be evacuated and the gas will eventually find its way to your aquarium introducing a large dose of carbon dioxide into the aquarium and result in a drastic pH drop.

Bob Goemans

Marine Technical Concepts, Inc., 225 Godwin Ave., P.O. Box 297, Midland Park, NJ 07432, (201) 444-7165, FAX (201) 444-5825,

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