this is my second bubbler grow. advanced hydroponic nutes. ph~6. temp 25c. humidity 40-50%. trying to keep it low. i didnt do enough pruning during veg. so now wondering should i cut them anymore in flowering?.
Stretch after Flip to Flower varies greatly from strain to strain. I have no experience with Iced Grapefruit so I can't offer a guess on how much she will grow during the next 3 weeks. WW and other Indica heavy strains seem to stretch less than Sativas, but that's not etched in stone either with so many hybrids popular nowadays. I say let the light prune it if need be. You didn't mention light type, but if LED then you might be able to grow them much closer to the lamp than most other technologies.