I also use the Lucas formula as a baseline for my nute regimen
(read: i don't follow it strictly and adjust to get the results i desire).

I use tap water ~120ppm.

VEG: (this is h3ad's formula from icmag)
0-6-9 ml per gallon plus 1 gram of epsom salt per gallon.
That brings my ppms to ~700. Every other watering is plain water. Hand watered coco and the plants look marvelous. No nute burn, no sign of deficiencies. Gorgeous.

FLOWER:
The target ppm for lucas formula is 1350ppm. basic lucas in flower is 0-8-16 ml per gallon. That is supposed to put your ppm right around 1350 and your pH around 5.8-6.2. Using 0-8-16 i always get left at 920ppm and 6.5 pH. I don't know why, but it happens. So i end up doing more of a 0-12-24 or 0-14-28 and that puts me right where i want it. The plants have just a tiny bit of tip burn so i know i'm right where i want to be.

It depends on your methods and what you are trying to achieve. If you want robust Veg growth...consider using Latewood's veg recipe of 1-1-1 (8ml per gallon of G-M-B).

hope that helps.
Skeet