nannochloropsis phytoplankton culture (questions)

[phyto4life]

I'm using a new bottle of F.A.F liquid f/2 fertilizer

I'll stick with this over miracle grow for the same reason due to adding it directly to a reef tank and I'm only culturing 6-8G of phyto a week

my brother-in-law has a bottle of FAF liquid f/2 that is 6 months old and used once should I risk using it because it will probably be another 3 month's or so before I use up the new bottle I just bought?

do you store the liquid fertilizer in the fridge or is it ok to leave it in a cool dry place?

8-10 day's to leave culture to a density of 3.5 cm on the density stick using 1/4-1/2 tsp of liquid f/2 fertilizer

does this sound close to what I should be aiming for?

do you turn off air when you measure the density?

do you use 16 hours of light?