Lots of nitrates being used

• pH:
• Temp:
• KH:
• GH:
• NH4:
• NO2:
• NO3: 1
• PO4: 2
• Iron:
• Dosing: 5 mL Flourish, 20 mL Excel, 15 ppm NO3, 1.2 ppm PO4
• NO3:PO4 Cumulative Dosing Ratio:

Notes:
Over the past week, I've been putting in a surprising amount of nitrates (at least 30 more ppm before tonight, after the initial water change dosage). I don't know why they're being used up so fast. Even the phosphates has been used up at a fast rate (added about 3 ppm). It also seems that reducing the dosage of Flourish from 10 ml to 5 ml daily doesn't seem to make any difference.

The last of the harlequin rasboras died today from that same sickness that has plagued all the rest of the rasboras.