cgrizzle I'm not expert but I've gotten good at reading leaves when they are ON the tree....sometimes to know what deficiency you have you have to know things like did it start with older leaves at the bottom or younger leaves at the top...is this the same effect on the WHOLE tree or just a specific area, when the WHOLE tree droops it could mean you over watered.... and if the whole tree droops over and the very tip of the leaves curl....YOU OVER WATERED AND OVER FED THEM so to get the most accurate advice, I would advise you to upload NOT just "a leaf"...lol lets see what I can do for you. Let say that it is an over feeding problem...tell me this. what are your ppms @ right now exactly. How do you take your measurments? PAY close attention to things like the "HOWTO" of things,...when testing for ph or ppms make sure you do so in water that isnt moving(in other words make sure you move any air stones and take your readings away from anything that moves the water,)some ppl take their readings right next to an airstone...doing so will give you the wrong readings..and could having u adding more nutes when u shouldnt. when you are taking your readings HOW? do u do ur readings? there are two ways you wanna go about this, first
1. If you have left your rez untouched and you come to take a daily reading, sit your meters in the water and let them sit for 2 mins first! Then as you put your meters in the water the numbers start to move around...but keep in mind that as your meters begin to match the temperature of the res for accuracy this takes this, 2 mins as mentioned earlier..now after that it should start to settle on a number and either slowly increase or decrease, what I do is once it settles on a certain number I count to 20 seconds, if it doesnt move THATS your accurate number!
now if you add nutrients to your res and take a reading 2mins later your gonna get an incorrect reading, because u didnt give the nutrients all the time it needed to evenly spread in your solution.
Anyhow:
in the case of ppms this could mean a 10 - 40 point difference.......There was a plant that wouldnt eat at 450 ppms but would eat at 440 ppms but ONLY after about an hour
so if you're OFF with your numbers they might not eat because its just to strong...which would mean you'd need to dilute your res
(which you can do THAT in two ways depending on much u need to dilute) I determine how I dilute my rez based on how full it is....If u have a 22gallon rez and you've filled it up to 21 gallons then u really dont have much room left to add RO water to dilute it, so what you do is scoop out 2 gallons of your rez water . and add 1 gallon of distill RO water u will add from this point you'll see how much it has droped your ppm numbers and from their you're good. Wit aeroponics when something goes back you know almost immediately if you are paying attention to your leaves
but recover takes about 3-4 hours at the lease and as much as a week depending on your problem.
Now in your case of this leaf show me some more pictures