Fresh saltwater testing low

[Reefer_madness78]

I recently started testing Ca Alk Mg with red sea test kit and the parameters where a little low in Dt. So I tested the saltwater before i did wc and they are the same. I've used saltwater from lfs (they use aquavitro?) And mixed my own with it reef crystals. I'm getting same results from both. Reef crystals says at 1.026 it should be Ca 455 Mg 1345. My tests keep giving me Ca 350 Mg 1000-1200. What gives?

 

[xxkenny90xx]

I think that's pretty standard for alot of salts to exaggerate their numbers

 

[Garf]

I recently started testing Ca Alk Mg with red sea test kit and the parameters where a little low in Dt. So I tested the saltwater before i did wc and they are the same. I've used saltwater from lfs (they use aquavitro?) And mixed my own with it reef crystals. I'm getting same results from both. Reef crystals says at 1.026 it should be Ca 455 Mg 1345. My tests keep giving me Ca 350 Mg 1000-1200. What gives?

Calibrating the refractometer would be my first job. Using solution at a known 35ppt. Randy Holmes Farley has got a simple DIY calibration solution on the inter web. Using DI water to calibrate at zero is very dodgy.