[mook]

Hi all,

I mix all the following chemical compound in one time.
              NaNO3(0.9107 g/L), glucose (0.5 g/L), NaHCO3(1.25 g/L), MgSO4(0.1 g/L),  CaCl2(0.027 g/L), KH2PO4(0.17 g/L), K2HPO4(0.65 g/L).
 
I found that the concentration of nitrate-nitrogen and total organic carbon (TOC) decrease to 130 mg NO3-N/L and 180 mg/L before I proceed to second step of my experiments.

Does anybody can tell what happened of this decreasing concentration? What should I do to maintain the all this concentration?