Yea i use silicates religiously up until day 18 of flower ...right around when they stop the stretch is when i stop using it . Thats interesting tho imma have to check into it ..I've read a few theories on the purple stems. Doesn't seem like anyone knows for certain. Are you running a silica supplement? I did read that silica seemed to stop it in several cases. I use it and have less purple stems than before but it doesn't fix all of them.