I find it hard to believe a temp drop to 64 degrees would do THAT! My room gets down to 68 or so once in awhile and THAT has never occurred. They look like they are waiting for noahs ark to come by so that can canoe off. It has to be something to do with your nutes.....lighting sounds good, so does your soil although soil is not my strong point by any means. I really like the idea of flushing the crap out of it and using something different.