Calcium reactors are fairly new in the aquarium world. They are systems that dissolve coral gravel so that it releases calcium, strontium, and many other elements into the water. They are expensive to set up, but once they are running properly, you don't need to add ANY supplements to your tank. They have a carbon dioxide (CO2)system to lower the ph inside the water column so that the gravel inside will dissolve, thereby releasing the elements into the water. The gravel dissolves better at a lower ph than marine tanks run at. Calcium reactors are simple to install, as all you need to do is drop the two tubes into your sump or tank. The pump for the Calcium reactor recirculates the water through the reactor over and over, and helps your tank to keep calcium levels over 400, and also boosts the alkalinity so that the ph in the tank will remain stable. They are expensive to set up, but once you get them running, are very inexpensive to operate. The CO2 can be obtained from welding supply houses locally. You can buy a bottle there, or rent one. They look sort of like SCUBA tanks! Refills of CO2 cost about $12-$15, and will last nearly a year, depending on the reactor you have. Most Calcium reactors don't come with the CO2 control mechanism. You will need to buy that separately. I have seen some places sell packages that include the CO2 valve set. The substrate in the reactor should be changed about every 6 months. It will cost you around $500 or more to get the system running, but it is worth it in the long run, especially if you are keeping stony corals. I am planning a large reef tank, and I have decided to go with the Marine Technical Concepts calcium reactor. It is more expensive, but I think it is the best one out there. It includes a second tube that is designed to remove any residual CO2 from the water before it is returned to the tank. It sells for about $700 and is rated for a 700 gallon tank. I love to set fire to money! Knop makes one that you can get with the CO2 control system for a little over $400. It is rated for up to 180 gallons. The beauty of getting a reactor that is rated for more gallons is that if you add another tank, you can plumb them together and won't need to buy another reactor! In my case, I could have my 180 gallon tank, and it could run at least 2 other 180's on the same reactor!
Sonny
