Quote:
Originally posted by Mad Reefer
Never had a Mg problem in 4 years now the Mg level is up to 1750.
...PO4(.1) NO2(0) NO3(0) NH3(.25) Alk(2.5) PH(8.4) SG(1.0262) Salitiy(37.6) T(82)
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Hey MR,
I notice your salinity is at 37.5ppt, sg of 1.026+, which represents part of your skewing for the value for your magnesium. Using a high quality salt mix will keep the conservative elements in the proper ratio to each other (assuming the water you use doesn't have large quantities of Mg in it to start with). This is true in seawater regardless of it's salinity, such that we need to measure the concentration of each of the conservative elements in terms of the chlorinity of the sample in order to determine if they are truely skewed from the standard ratio, or just higher or lower due to higher or
lower salinity. If the Salinity is 7% higher than standard seawater, then the amount of Magnesium will be 7% higher than normal standard seawater as well. For this sample this only accounts for a portion of your tested levels.
Craig Bingman has done some computer modeling for continued use of Calcium Chloride additives when supplementing both CaCl2 and Ca Bicarbonate as the source of calcium and alkalinity (i.e., 2 part buffer additives, or reef builder type buffers and CaCl2) in reef aquaria systems. The short version of the story is that several of the conservative elements become skewed in terms of the chlorinity of the water column, notably Magnesium, sulfate, sodium, potassium, and alkalinity. His conclusions (I am taking a few liberties here) are basically summarize as ...without regular water changes to reestablish the conservative nature of the water column, the use of additives for Ca and Alk will gradually skew these values to beyond recognition as normal value seawater... (THIS IS TOTALLY PARAPHRASING AND MY INTERPRETATION of CRAIG'S WORK, not a quote from him). Without getting into a long discussion of why this occurs (different chemical sinks and biological utilization of these elements in the ocean is relatively small when compared to the percentage utilization (very high) in most home aquaria), I can see how your Magnesium could become this high, more so if you don't perform regular 10% seawater changes and you have a large population of calcifying creatures in a well established tank.
Prolly not the explaination you were looking for, but a good possibility of what is happening, especially in view of your statement that you don't supplement any Mqgnesium (i.e., epsom salts, etc)
Hope this helps, bringing your salinity to 35 PPM and doing some large water changes with a good qulity mix and RO/DI water will help if the underlying causes are related to this discussion.
