The ppm is a good place to start at, starting low and working upl
It takes the plant 3 days to let you know its doing good. I usualy run about 1500 that includes the background. I go for a 1/8 inch leaftip burn. That maximizes the TOTAL power. Cumming up to bloom I start backing it down to 1200 a week than 1000 over background
Background is what you get out of the tap water.
If at any time you plants look goofie/birnt flush the hell out of them and start over.