Brown leaves - what am I doing wrong, folks?

I would guess that they are burnt due to a too strong nutrient solution. This particular Haze has 90% Sativa genes, which means not so much nitrogen is required to grow these plants, with moderate to light levels during veg and only moderate at best, during flowering. I would expect that if you were to reduce the strength of your nutrient solution, this problem should disappear and without any loss of growth rate. Most nutrients are a "middle of the road" compromise to cover the whole spectrum of plants from pure indicas, hybrids and pure sativas. The fact most people grow hybrids makes the "middle of the road" approach seem logical, however, pure indicas could probably handle a stronger mix without problems, where as pure sativas could be well and truly over fed, even when used at the recommended dilution rate. The fact that this strain, Expert Haze, is 90% sativa and with the symptoms she is showing, would suggest to me that she is being burnt by the nutrient solution, due to the fact of her high percentage of sativa genes and sativas like this not requiring as much nitrogen as "middle of the road" hybrids and nutrient solutions. Hope this helps,..... Organoman.

Appears to be a cal mag deficient issue for sure. Possibly a nitrogen deficiency as well. A full spectrum light would be highly recommended. If current light has both use both always. First check your ph with a calibrated ph tool. Also take pictures in white light so people viewing can see issues well. If ph is in range then further nutrients are required. Good luck and happy growing 🌲🌲🌲👊