What’s happening

Hi buddy, Must be concerned with your grow. First of all, your problem is for sure casued by water stress. I see a fella directing to over watered but your case seems like water shortage so opposite to overwatering. Of course, we need more contents to fully diagnose but the recommendation is... 1. Lower light intensity if thats the case. 2. Check if your exhaust fan is too strong, which makes aggresively dry environment. 3. Irregular watering * all three cases happen extremely often to all the growers tho it is really easy to fix if the problem is caused by strong light or strong vent. Another thing is, you may have iron deficiency but unlike the fella mentioned, iron deficiency happen due to high pH. Depends on what iron chelate you use but probably it is EDTA or DTPA and each can handle up to pH of 6 and 7. That means if your rootzone pH is near or above 6 or 7, your plants are not uptaking iron. And your Mg deficiency often caused by irregular watering or small root mass compare to above ground mass. So I assume when you can dial the cliamte, you will not get this nutrient deficiency. So maybe focus on climate than the nutrient. Anyway, happy growing!