unlike ppm(which can vary by strain or particular conditions) PH determines the plants ability too absorb and process nutrient.there for the 5.5-6.8 applies to any method,although as you say soil will maintain the higher end w/out negative effect.

P.S. whether in veg. or bloom i run my ph at 6.0 (hydro)
divestoned Reviewed by divestoned on . Newbie pH, and flowering questions. About 3 weeks ago buddy popped by with 7 Northern, and 3 Afghani clones, already well rooted, and already zig zaging leaves(I'll bring that up later). Anyways they had to sit in the little rockwool cubes in a 90 degree closet for 2 days while I restocked(it's been a while). It was pretty much a take them or they chuck them situation. Anyways, I got the dryer set up and got them in pots of sunshine mix under a 400 watt MH bulb. We started advanced nutrients, grow, micro, and bloom. Picked up Rating: 5