Quote:
Originally Posted by christyf5
Thanks Mark. I just heard back from Kent and they do their lab testing at 1.020-1.023 and get Ca = 480, Alk = 9.0 dkH, Mg = 1280ppm.
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If that is indeed those are their testing parameters, then that is pretty sad. They should be standardizing to one specific gravity value.
Salinity is a pretty linear relationship, 480ppm Ca at 1.020 should yield about 480ppm x 23/20 = 552 ppm at 1.023 and 480 x 26/20 = 624 at 1.026. On the other hand, if 480ppm is at 1.023 then it should yield 480 x 26/23 = 542 at 1.026. Higher salinities will yield higher Ca, Mg, and CO3 concentrations because are you are adding more of it to the same volume of water.
So I see three possibilities:
1) Your hydrometer/refractometer is out of calibration and you are actually making water to a higher SG than you think you are (and your tank will be running at a higher SG than what you measure).
2) Salt mix is out of whack
3) Your freshwater used to make up marine water is high in Ca, MG, and CO3.
If you are using RO/DI then #3 is unlikely (could test the freshwater anyway). If you have tried a second bucket then the possibility of #2 is lower. I would start with #1...
HTH