Gorilla Zkittlez in mineral wool

Day 15: Cut off the burnt tips on the first true leaves. New foliage looks green and healthy. Recalibrated pH meter. It seems readings were inaccurate the last few days. After calibration the solution appeared to be 5.2, while I was adjusting to 5.5 before. Had to flush the Uni-slab again with proper solution. Runoff EC 0.86, 430 ppm, pH 6.2. Going to place the rooted cube onto the slab tomorrow when it drains enough. Day 16: Put the cube in the slab. No watering for at least one day to promote root growth. Day 20: Some edges on old leaves burnt, little Mg deficiency signs. Not sure if it’s actually a deficiency or pH fluctuations. pH in solution is drifting up from 5.5 to 6.2 overnight. About 30 ml of 110 ml dose is always left in the pipe which also impacts the rapid pH change when solution is applied. Runoff pH is 6.2-6.6. According to manufacturers recommendations I’m giving too little CalMag to my 40 ppm tap water. Increased dosage from 0.5 ml to 0.8 ml, and diluted solution to get the same solution ppm as yesterday. Thinking about increasing EC to 1.0 to maintain the same NPK ppm. Just waiting till runoff ppm lowers a bit.