R All I can tell is R
Can be potassium deficiency. Leafs looking like that. Make a search about that. Compare pictures with your plants.

Again, before watering, check the soil from top and from drainage holes, and the weight. After all, be sure its completely dry (not like desert). Since the plants are small, top of the soil can get dry but bottom can be still wet. Adding a little water from top can supply water for upper roots in this case.
Some things yo used are not familiar to me. So, I don't know if there is anything else to say. Wait for more responses.

Hope you can cure them fast and easy. Good luck.:hippy:
tevfik Reviewed by tevfik on . Help with Unusual yellowing of older growth + rusting inner ridges (PICS) What is your experience level? Novice Your Equipment: .1) Type and wattage of lights. 400W CMH .2) Distance from tops? 20" .3) Reflector type? batwing .4) Is there a consistent fresh air supply? yes .5) Do you have an exhaust fan and a circulation fan? yes Your medium: Rating: 5