I'm an an*lytical (ridiculous that it won't let you spell out that word!) chemist. Here are the ideal ranges I keep on my test sheet. The ranges came from a few sources (don't have those now) but should be pretty close to what you want for a nano reef.
Temperature - 75 to 82 degrees F (I keep mine at the low end)
Salinity (specific gravity, SG) - 1.023 to 1.025 (I keep mine at 1.025)
pH - 8.1 to 8.4 (my tanks run near 7.8 though with new water near 8.3)
Alkalinity - 3 to 4 meq/L or 150 to 200 ppm (I add buffer with the make-up water)
Nitrate - <10 ppm (zero for most test kits)
Nitrite - 0
Ammonia - 0
Calcium - 412 to 450 ppm (hard to achieve)
Magnesium - 1288 to 1320 ppm
Phosphate - <0.05 ppm (requires a specialized test kit or HPLC with anion detector which I have at work; basically you want zero; I keep RowaPhos in my filters to collect phosphate, and I start with RO water)
Good luck!
