Ran it again using the reefbot and got 0 ppm again. Ran it manually and could not tell the difference between colors. Giesemann is really useless and expensive (by requiring so many test kits to be run).
Here are my comparisons so far:
Alk (Salifert) works well and matches Hanna manual testing
Alk (RedSea) is off by 0.2-0.3 dKH from Hanna manual testing.
Ca (API) works well and matches Salifert manual testing.
API (nitrate) can only report 0 ppm, 5 ppm, 10 ppm, etc. It needs better resolution at the low end. My Salifert manual testing was 1 ppm and Reefbot (API) reported 0 ppm.
Mg (RedSea) is off from Salifert manual testing by 75 ppm.
PO4 (Giesemann) is off from Hanna ULR by 0.1 ppm
I hope reefbot can get some better phosphate and nitrate test kits working because right now, I am not ready to let Reefbot automate those tests because it does not give me the accuracy or resolution I desire. Not sure the RedSea Mg is worth using up 3 reagent vials for unless it proves more accurate than Salifert manual testing. I'm not sure which is correct.