I definitely agree with Rock on most of his LL disertation.... I use full strength but burned a 2 week old Nexus with the stuff even following directions to the letter and in fact using less light than recommended on the bottle instructions.

In speaking to my hydro guy awhile back he mentioned that he thought using LL twice a week "was plenty" despite the company's stating it can be used every other day and that it was perfectly safe on any rooted plant over a week old. I've definitely found those two statements NOT to be in "the plant's best interest."