By Bob Goemans
Site Supported in Part by:
Premium Aquatics 

Pro-cal Calcium Reactor

Manufactured by: Marine Technical Concepts

A product review by Bob Goemans

Pro-Cal Calcium Reactor:

(Written in 2003)

Think about a reef aquarium where you did not have to prepare and add Kalkwasser, and/or dosing other type calcium additives. Imagine not adding buffer, strontium, and even trace elements. Wouldn't it be nice not fighting the calcium and buffer war where you add calcium one day and buffer the next day only to find that the following day calcium level is again low. You then add more calcium and find the next day the buffer is low again. Imagine having a very stable reef aquarium environment where, without adding any additives, calcium level remains in the 400's, and alkalinity can remain between 12 to 14 dKH! Imagine your supply of additives reduced to only iodine! Well, that is very possible if you have a Marine Technical Concepts Pro-Cal Calcium Carbonate Reactor connected to your aquarium.

The Pro-Cal base plate has a footprint of 13 x 15 inches. Mounted on this acrylic plate are two 19 inch tall, clear acrylic cylinders. One of the cylinders is equipped with a pressure gauge, a prefilter, and a glass bubble counter for controlling carbon dioxide (CO2) gas flow from your CO2 equipment. Also mounted on the base plate is a Little Giant Model 2 MDQ-SC circulation pump which draws water from your aquarium, flows water through both cylinders, and returns calcium laden water back to your aquarium. Let me take up a little space here and describe setup and function of this equipment. I think it will help make it very clear just how the Pro-Cal operates and why it can provide a very stable environment for your reef aquarium.

When you purchase this equipment, it comes to your door packed in a custom foam enclosed container. The worst possible shipping conditions probably would not harm this unit! In fact, the unpacking time frame will probably take you longer than the time needed to actually get the unit running. Just kidding, but it sure is well packed! Once the unit is located, either at the same level of your aquarium or sump or below it, the tops of the two cylinders, the Reactor cylinder and Post Reactor cylinder are removed. Per the instructions, which are written and also enclosed on videotape, the cylinders are filled with aragonite gravel. Crushed coral could also be used, but aragonite is a better choice. They are then filled with fresh seawater and the covers reinstalled. A bracket holding the suction and output lines of the unit is then attached to the top edge of the aquarium or sump wall. The suction line is adjusted so that it extends down into the aquarium water. The output line is adjusted so that its height is always slightly above the highest water level in the unit where installed. The bubble counter on the Reactor cylinder is now filled with freshwater. When this is completed, its time to plug in the circulation pump and per the instructions, adjust flow through the unit with the Post Reactor's needle valve and high quality, calibrated glass flow meter. Now its time to connect your CO2 line to the bottom of the Bubble Counter and adjust your CO2 regulator to deliver a steady stream of bubbles through the Bubble Counter. Keep in mind that this whole procedure is shown, step-by-step on the supplied videotape.

The flow of CO2 into the Reactor cylinder will pressurize this cylinder and supersaturate the solution inside this cylinder which in turn drops its pH to about 5.5 This causes the aragonite, which is mostly pure calcium, to slowly dissolve. In fact, the aragonite will probably have to be replaced in both cylinders on a yearly basis. Keep in mind 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. Now, here is where the Pro-Cal differs from other calcium reactors: calcium laden and heavily CO2 saturated water flows from the Reactor cylinder to a separate cylinder called the Post Reactor cylinder, where it very slowly passes through this aragonite filled, un-pressurized cylinder slightly raising the pH to about 6.5 and "dissipating" over 95% of the dissolved CO2. You can bet that all those other single cylinder calcium reactors on the market are going to be thinking design change after seeing the Pro-Cal! Considering that the units effluent is in the range of 40 dKH, you could easily maintain a calcium level in the 400 to 500 ppm range, and have a stable alkalinity of about 12 - 16 dKH. Besides that, aragonite also provides trace amounts of strontium, magnesium, and iron.

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 Wojcik or his brother Jeff, they "will" personally take your calls and spend the necessary time to answer your questions and insure that you will be a happy customer.

Another interesting point about this equipment is that Leo's Pro-Cal unit has been running for a year and there has never been any deposit of calcium carbonate on any of his system pumps. Imagine that, not having to clean clogged powerheads because your Kalkwasser has precipitated out of solution onto the motors internal parts. If you hate the word "maintenance" as much as I do, contact Marine Technical Concepts and request further information.

Before I close on the review of the Pro-Cal, I want to again note that the Pro-Cal does not come with a CO2 bottle or regulator. These are something you will need to supply and there is some thought on this subject matter that you should be aware of before you purchase this equipment. First, I highly recommend you purchase your CO2 bottle from a local welding supply company. Bottles come in different size, i.e., 5, 10, 15, 20 pound and larger. But, since you are going to refill the bottle at some point in time, your local welding company may not want to refill a bottle they have no safety record on. For safety reasons and your convenience, I recommend you procure your bottle from a local welding company. Next, it would 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, CO2 will continue to flow during a power outage, evacuating water in both cylinders and then find its way to your aquarium, introducing a large dose of CO2 into the aquarium. Finding a company that sells a regulator equipped with a 110V solenoid can be difficult and very time consuming. My search for this item ended when I called UltraLife Reef Products. Not only did they know exactly what I was looking for, but it was a normally stocked item! Great service and a friendly group of people! Give them a call when it comes to getting your regulator.

In the first month of operation of the pre-production model that Marine Technical Concepts sent me for evaluation, I have not used any additives to my 125 gallon NNR reef aquarium except iodine. Calcium holds fairly steady at 440 ppm, morning pH is 8.05, while evening pH goes to 8.3, and alkalinity is 11.2 dKH (4.0 meq/l).

Will I miss adding calcium and buffer to my aquarium? Will I miss not having a closet full of additives? Will I miss cleaning my powerheads of calcium buildup every six months? Will I miss taking lots of calcium and alkalinity tests? Well, it took me all of two seconds to come up with an answer!

(Follow up in May of 1997)

In my past September column, I discussed the merits of the Marine Technical Concepts Pro-Cal Calcium Carbonate Reactor. If you missed that Marine Fish Monthly issue, this duel cylinder, aragonite filled calcium reactor uses carbon dioxide (CO2) to slowly dissolve calcareous aragonite gravel. The effluent from these cylinders flows to the aquarium where it maintains aquarium calcium and alkalinity at or above natural seawater level, all without adding Kalkwasser or other type calcium additives and/or buffers. At the time I wrote the September review, I had only operated the reactor for one month. Yet, my calcium level was already holding steady at 440 ppm, with morning pH at 8.05, evening pH at 8.3, and alkalinity at 11.2 dKH (4.0 meq/l). Yet, there was minor tweaking during the first few months of operation that raised some questions. Leo Wojcik, owner of Marine Technical Concepts and I discussed these puzzling situations and the results of our conversations should benefit new and future owners of this leading edge equipment.

One of the first noticeable situations was that over the first few months of operation the alkalinity level of the reactor's effluent fluctuated. One week I would find it to be 30 dKH, the next week 18 dKH, and then the following week at 40 dKH. Yet, the effluent return rate of approximately 120 drops per minute never did cause any radical change in the aquariums' alkalinity level. It simply ranged from 3.5 to 4.5 meq/l. Contributing to this unsteady level of alkalinity in the reactor's effluent was an inability to control the CO2 bubble speed through the units bubble counter. I would get the correct one bubble every one to two seconds only to find a few hours later it slowed to one bubble every five or six seconds or slower. It was also necessary to vent the main reactor cylinder twice a week as one inch or more of air space would buildup at the top of the main reactor cylinder. This "air space" reduced the amount of CO2 that would flow into the cylinder, limiting pH decline in the cylinder and thereby the amount of liberated calcium from the aragonite gravel. Also, even though I filled the main reactor cylinder to the proper level, the force of the water being injected into the top of this cylinder caused gravel particles to bounce around the top portion of the cylinder. Some of these particles came to rest on top of the pivoting CO2 override assembly, interfering with CO2 flow into the cylinder. Furthermore, the force of the water flow into the main reactor cylinder caused aragonite particles to "mound." One of the high points of these mounds was directly under the rear portion of the pivoting CO2 override assembly, possibly interfering with movement of the assembly. Also, air bubbles occasionally filled the output line and/or flow meter. This required frequent use of the needle valve to bleed off the trapped air.

Well, what caused these blips in the start-up of this equipment? First, I used an aragonite gravel that was too small. This was the major contributor to my perplexing situations. Most of the above mentioned circumstances could have been avoided if I would have used aragonite particles that were about 5 - 7mm in size. I used a small 2mm size particle. With the larger particle, better water flow through the aragonite would have quickly cleaned out trapped air bubbles between the dry aragonite particles. Also, a larger medium would not have been affected by the water force at the top of the reactor. Therefore, there would not have been a mounding problem or aragonite particles deposited on the pivoting CO2 override assembly. Also, there would have been fewer adjustments to the CO2 bubble rate. Now that the unit has been operating for eight months, the height of the small aragonite particles has fallen three inches thereby eliminating the build-up of particles on the pivoting CO2 override assembly. There is now no build-up of air at the top of the main reactor cylinder, which is the way it should be, and CO2 flow remains steady at one bubble every one to two seconds. The bleeding off small pockets of air in the output line and/or flow meter still occurs, but does not interfere with flow to and from the aquarium.

Now, after eight months of use, the calcium level in my 125 gallon NNR reef aquarium is holding steady at 480ppm, morning pH is 8.23, evening pH is 8.44, and alkalinity is 9.8 dKH (3.5 meq/l). I have not added any calcium or buffer additives since I first started using the Marine Technical Concepts Pro-Cal Calcium Carbonate Reactor. I should note that this equipment costs' $695.00. As one reader put it, you can buy a lot of buffer for that kind of money. Yet, for those hobbyists who can afford quality equipment or have grown tried of measuring various chemical additives, the Pro-Cal Calcium Carbonate Reactor will provide a very stable calcium and alkalinity environment. In fact, the only additives I have used these past eight months are iodine and Marc Weiss Vital products. By controlling CO2 flow and water flow through the reactor, aquariums up to 500 gallons can experience levels of calcium and alkalinity at or above natural seawater. You just do not know how nice it is not to bother with Kalkwasser until you have one of these units!

Before I close on this subject matter, I should note the September column also made mention powerheads would remain free of any calcium build-up even though the reactor provides an abundance of calcium. To check this out, I recently removed some of my regular powerheads for their normal cleaning. None had any accumulation calcium on their magnets or shafts. Without a doubt, if you can afford this equipment, you will be pleased with the results and so will your stony corals.

Bob Goemans

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

More Reviews
Site Supported in Part by:
Boyd Enterprises