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Originally Posted by cozmo911
I have had My new Calcium Reactor hooked up for a little over a month... ...when i test for Calcuim i am getting a reading of 350 (PPM). When i check for Alk it is at a high reading of 12.8 dkh.
...Is it just a matter of time for my Ca levels to go up? ...I have just a few sps for now, nothing to really lower the Ca readings
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Part of the issue here is that using a Ca reactor is a slow method of building your levels, even if there are only a few organisms that sequester calcium and alkalinity from the water column. Organisms that take these substances do so in equal amounts in terms of the number of molecules they use to make skeletons, tests, shells, etc (equimolar consumption). This means that we must provide the calcium and the (bi)carbonate in equal amounts and supplement back to the water column in a similar manner. We do this at the optimum level when we reach the highest supersaturation quotient possible for seawater, but at the point where there are approximately equal numbers of molecules of both components (equimolar supersaturation).
Remember that the supersaturation quotient is a product of the actual concentrations of the two components of the buffer system and the calcium level in the water column divided by a constant determined by the conditions of that water column (see
this thread strting about post 25 ). The net effect of this is that high Ca will equal low alk, and
visa versa as the amount of the component in excess will precipitate out equal amounts of BOTH components until equilibrium is reestablished. This means if you have 700
PPM calcium (an exaggeration) and 5 dKH alkalinity, more than likely the solubility quotient for calcium with respect to the bicarbonate/carbonate concentration will be the same as if the Ca were 450 and the alk were 10 dKH, saturation is saturation, regardless of where the individual components are with respect to each other. If you were to add more calcium, the calcium added will remove CaCO3 as a precipitate, so both the added calcium AND THE ALKALINITY (bicarbonate ion) ALREADY PRESENT IN THE WATER COLUMN will be REMOVED from the water column, dropping both calcium and alkalinity from the total picture as CaCO3 precipitate. You could add instead more alkalinity, which would initially have NO effect on total alkalinity (because it would be precipitated as CaCO3), but would begin to drop total calcium as BOTH COMPONENTS would precipitate as calcium carbonate. Once the excess Ca is removed, alkalinity can build to the point that both components are balanced, and you will be able to allow the reactor to provide the balanced amounts of both Calcium and alkalinity to maintain your water column parameters at around 425 to 450 PPM calcium and 10-11 dKH.
This would occur only if you provide the alkalinity to the point that you would bring the water column to balance with respect to both calcium AND alkalinity levels. If you were to continue to add alkalinity to the excess, calcium will continue to precipitate out as Ca Carbonate, and the levels of alk will climb until the new supersaturation quotient is reached with respect to the amount of calcium left in the water column. At this point, calcium and alk will both precipitate out in equimolar amounts until the next supersaturation quotient is reached, ultimately reaching a point where calcium will be very low and alkalinity will be very high. The trick is to get to a balanced solution by adding whatever component is deficent, where the supersaturation quotient will allow for equimolar amounts of both calcium and bicarbonate/carbonate to exist, then to replace biological sequestering in equimolar amounts by whatever supplementation method you choose.
Sorry to be so brief, gotta get the yard ready for the daughter's birthday cookout tonight, as I have the trick recipe for S'mores now, and I need to get the bonfire ready to light!
HTH
