FastBuds OG Kush + NASC Skunk #1 Auto

The flowering process is well underway for both of these girls now. They have both been much thirstier than they were during the vegetative phase and I find myself needing to water them approximately ever 48 hours. I have continued feeding them the Jack's nutrients but recently I have started to notice some yellowing on the tips of some of the newer growth. On a few of the leaves the tips yellow tips have turned brown after a few days. I am unsure of exactly what might be causing this. Nute burn perhaps? Or light burn? Possibly a deficiency? Fortunately both plants still seem to be moving right along so I am not overly concerned at the moment. Still, I would like to identify the problem so it can be corrected. I performed some more LST on the OG Kush this week (on day 40 to be exact) by tying down all of the main branches so they were all at a similar height. Within just 36 hours all of the branches have started turning back towards the light and the mid section of the plant that had previously been blocked from getting light has exploded with growth. I am incredibly pleased with how great the training has been going and I plan to readjust the branches again in a few days. The training went so well on the OG that I figured I might as well do some training with the Skunk as well. This plant was a bit trickier since the stems are already so thick. I did manage to pull several of the main branches down and away from the center of the plant and tie them in place with gardening wire. Hopefully she takes to it as well as the OG Kush did! During this process I also performed some light defoliation. I removed a few of the lower fan leaves that had started to yellow as as well as two or three leaves that were blocking bud sites.