I'll tell you a few things, if you run the water to waste, to figure out the good amount, if you water too little all the time, salts will build in the cube, so what you want to do is water so there is enough runoff pouring out to the point when EC and pH you put in is coming out the bottom the same, then you never get buildup, it doesn't take much its not a waste in my opinion and too little and you'll have buildup having to flush all the time. the peeps that dont this work on a schedule of flushing the cubes and system every week or so, but why, with a little runoff each time output coming out almost the same as input, plants get full balanced nutrient whatever you feed each time and doesn't build. Also, consistentcy with watering schedule of rockwool is very very very important. it's best the first times to flip the switch by hand water them all, then you wait and when they are quite dry ready for more water, you back up the timer 30-1hr before they got that dry, perfect. because if you water cubes too much is also very very bad. Your plants are very dark rich green they do not, not have enough food, you oare wrong I'm sorry. I can see. you're on the verge of overdose. The issues with the leaves is the roots. damaged roots can show all kinds of wierd shit on leaves. they are directly related. I hope this helps. pH 5.6 is the sweet spot not 6, for rockwool, a little drift to 5.9...6.0...6.1... wont hurt, but 5.6-5.7 is the sweet spot for cubes for plants to have best uptake. and keep water no less than around 65 and no higher than around 70, temp in the middle is good. This is rockwool growing bro. Grow monsters. if light is beaming on table hurting roots, cut pieces of plastic for blockage, but plants leaves/canopy will block it once bigger more bushy. Good Growing. wrote that without taking a breath like if somebody spoke in one long sentence with no comas or pauses..LOL turbo typed so hope it makes sense. BONG!