A calcium level at 220 is very questionable and unless you were only dosing alkalinity for an extended period of time, it's pretty much impossible to get that low. When calcification occurs, as in coralline algae growing, corals forming their hard skeletons or abiotic precipitation, a defined amount of calcium, alkalinity and magnesium is used. That rate is aprox. 20ppm calcium to 2.7dKH alk
and 2ppm mag. Now lets assume your water was in the normal ranges of 420 calcium, 10 dKH alk
and 1350 mag. For your calcium to drop 200ppm, your alkalinity would need to drop 27 dKH
, but there isn't that much alkalinity in the water. The only way it's even remotely possible for calcium to be that low is you either have a very high demand for calcium (either thru hard corals growing, lots of coralline growing or some precipitation events) and only dosed alkalinity or the test result is faulty. Also keep in mind once calcium drops below around 360ppm it becomes very hard for calcification to occur which would slow the demand for calcium.
A calcium reactor is a fine way to maintain calcium and alk
if you have a tank with lots of stoney corals and a high demand for calcium and alk
. It is, however, somewhat expensive in start up costs being you need the reactor, co2
bottle, regulator and pH controller and is somewhat hard to dial in when you start it up.
PhosBan reactors work fine for running either GFO