Yeah all of those factors can cause your symptoms but a picture would really help us identify your problem.nute burn, under watering, to much wind on the, high heat, light stress.... many different things, as always a pic would be most useful
actually they all can cause this. plants transpire, almost like people do when they sweat, to keep themselves cool so if you have high heat the plants will transpire more and lose more water thus sucking the plant of its water, if the room has high winds what happens?? yup you guessed it the plants moisture is blown off leaving it to continuously transpire with no luck. you could always mist your plants one or two times a day to help them out, i do this for low humidity reasons.I'll Post a pic tonight, just trying to get some objective views, it seems pretty unlikely that ALL those would cause brittle/crumbling leaves.
Your right with the ph, and a good flush back off some with the nutes and your all goodOk I flushed the plant, runoff is 6.1 ... is that a bad thing? Going in, the water was PH'd at 6.8. And Johnbudz, what the heck to you mean 6.7 PH is way too low? lol. Thats about what you want it at in soil my friend.
Roger that, I'll flush again after letting her dry out for a bitYour run off needs to be as close to soil levels as posable. High 6.7 to 6.8 being target.
If its close to 6.0 then flush with 3x the volume of the bucket you might have to do this
More than once to keep your ph run off in check