Calcium reactor kalkwasser reactor help

[Nascars]

I have a 50 gal reef tank with mixed corals. I'm wonder which is better for me to get calcium reactor or kalkwasser reactor? What is the difference between to two?

[MrRyanT]

Not sure I can explain all the differences, but if you can maintain proper alk and calcium with kalkwasser it is much easier and cheaper to set up. If you already have an ato then its really easy to set up.

[Hal]

A calcium reactor relies on injecting carbon dioxide into the media chamber. You put a high calcium media (looks like crushed shells or crushed live rock), and this dissolves the media releasing calcium into your water. You generally need to re-oxygenate that water to blow off whatever residual CO2 is in the output of the reactor. You'll need to buy the media chamber, CO2 tank, and regulator/valving. Many people also add a pH probe on the output of the reactor to monitor its performance. In general a calcium reactor will run you several hundred dollars for initial setup, and then you need to yearly replace the media. Depending on the size of the CO2 tank, it should last several months before a recharge is needed.

A kalkwasser reactor (also known as a Nielson reactor) is a media chamber that you partially fill with kalk. I usually use 2-3 cups of kalk at a time. Included with the reactor will be some type of mixing device: either a stir bar or a small powerhead. Personally I prefer the powerhead as I've heard too many issues with the stir bar style. Most people then feed their auto-topoff through the kalk reactor so that everytime topoff is added the tank gets kalk. Typical cost for a reactor is $100 plus another $20 or so for a gallon of the media, which should last a year or more. The only other thing you then need to do is to periodically mix the kalk. Most recommend once or twice a day, and use a digital timer to control this (about 30 seconds of mixing each time). Manually plugging in the power chord works just fine too. An analog timer won't have the 1 minute precision that you'll want.

I don't know anyone that uses a kalk reactor without an auto-topoff.

A kalk reactor will generally be the cheaper way to go. Most recommend starting with this, and then if you still can't keep up with your calcium needs, you add the calcium reactor. For a 50 gallon tank I would be surprised if the kalk reactor doesn't take care of everything.

Lastly, some people use the "slurry" method for kalk. They mix a slurry of kalk and water, and then manually dose a cup or so at a time. As long as you do this in the sump, it usually mixes with your normal tank water before it deposits onto corals/fish (which you wouldn't want to happen).