this tidbit of info...I for got to mention...Since you asked about how long nutes will last; this might help.

3-part
I dont' use much grow...A liter bottle last me a couple grows...
Micro a liter per grow...
Bloom, You use alot more bloom than the others, because generally People are not "Vegging Long" on Strong nute formula's, they spend more time on the flower photoperiod. I buy a gallon of Bloom

Liquid Karma...Buy a gallon...same with Calmag+ (you will love this stuff and want to use it, so this advice will save you a bunch of money(buying little bottles @3x the price))...Hygrozyme fits in this category, if you are going to have large perpetual grows. you still save a wad of cash, if you buy can afford a gallon. lw