I have 4 plants from bagseed in a bubbler hydroponics setup with Foxfarm nutes (no ppm meter so i did recommended amount on back of bottle) in a 10 gallon container. Plants are about 7 or 8 weeks old and filling out nicely with no problems except some of the newer top growth leaves are curling not at the tips or edges but right down the base of the leaf's spine. The curling is like the leaf is arching it's back but it does not run the length of the leaf just about half way down only in the center. Some of my leaves look a little ruffled and darker than usual too. Interestingly enough when this happened to 2 of the 3 indica plants, the 1 sativa seemed to get healthier and experience a growth spurt. Maybe it was just when it would have happened anyways but it definitely shot up at the same time the others started to have problems. Any ideas? They don't look bad and i just changed water/nutes and corrected ph to 6.8