two weeks ago i posted a thread about my leaves curling and changing colour from the center i was advised to cut down watering and nute as they were only seedling and to have my ph at 5.5 i did the above i cut the nutes right out so now it only getting water my ph in my tub is 5.5 and i let it get to 6.0 before i drop it back down and i water them on mondays and thursdays they started to come good getting there colour back. i didnt check them from last friday till the monday and in them days thay started going brown at the tips and drying out and the leaves a getting lighter again though this time the light is on the out side of the leaves when last time they were changing from the center of thr leaves
HIGH All, the damaged leaves will grow crispy nothing you can do about that. Ok time to put nutes in again....try just a 1/2 of what your recommened dose says and grow from there. Edit: your quetion about PPM...Here read this from Fet.
yup uno is right time to put nutes in there again nitrogen is the problem here i would start the ppms at 200 and then as they get bigger increase every strain is different with nute requirements and care your ph is fine, they just need some food in the res what nutrients are you going to be using?