KrazyKuch's & Michika's 180Gal Tank Build

[Delphinus]

Found them online - http://www.americanmarineusa.com/NO3monitor.html

Sort of buried near the bottom it says "Calibration is recommended before each measurement."

I'm not sure if anyone local has any, but you can MO new calibration fluid from J&L. Probably wouldn't hurt to have some extra onhand. I find the calibration fluid only lasts so long before it seems to drift. I would think that the residue of the 1ppm fluid would eventually start to pull down the 10ppm fluid. (Having said that I seem to get a few months out of each, so the stuff lasts forever anyhow.)