Tell me, please, that it's a typo when you say you're giving 20,000 ml/L of your nutes... please tell me that's a typo!
Droopy leaves like that are usually the result of one of three things - overwatering (the state of being constantly wet - NOT the amount of water you're giving at any one time), underwatering or nitrogen toxicity.... You say you're only watering when the soil is STARTING to dry so I happen to think you're overwatering here. You've got to let that soil dry out completely - pick up a pot to see if it has any weight in it - if it does, don't water... if it doesn't, water away!
And while your pH isn't terrible, a lower pH (between 6.0 and 6.5) would be far better... 6.2 would be ideal...
Good luck....