both veg and flowering. the key is to make sure ppm increases GRADUALLY. one more thing drmaryjane, be careful with "ppm" quotes, they are often misleading. ppm is not a universal measurement, it is used differently by different companies/users. for example, it is often read as "ec x 700" or "ec x 500" where "ec" stands for electrical conductivity. the only standard measurement is electrical conductivity, which for us will range between 0 and about 4. if you naively listened to that gentlemens quote of 2000 ppm at a conversion rate of ec x 500, u would surely kill your plants in a short period of time. hell, even at x 700 conversion they're bound to get burned. i stick with ec since it is universal, and it should range from 1.2 for clones to about 2 for plants in vigorous veg stage. that's 1400 ppm @ x 700 conversion and 1000 @ x 500 conversion at peak feeding levels. i don't know what kind of conversion that gentlemen is using to feed his plants 2000 ppm, but its off my scales.

best advice i can give is just go by the directions on the box/bottle. they are designed to give you adequate ppm levels without having to measure afterwards. a note about those numbers - they are designed for systems using ro water at 0 ppm. if you're using tap water at, say, 200 ppm, you'll want to add that much to whatever number you end up with to match it with the company charts. hope this helps, peace.