PH

Your PH is 9? and EC is 4? that's quite high. You can alter your PH by flushing the medium with just ph adjusted water. This in turn will also flush out all the extra nutrients and lower your EC down to a normal amount. Normally 20% runoff is enough to keep it in check but if your overfeeding to begin with it may not do jack shit. I also never water till runoff when I grow in soil. I always just water till a few drops come out as it can compact quite easily and become waterlogged. You should monitor your feeds PH and EC before going into medium and after if you are watering with runoff. The first little bit is always going to be higher, try and collect a sample after a bit has come out. Any PH down will work, I tend to lean towards phosphorous acid. Good to calibrate your monitors/pens to ensure they are correct as the plants are looking descent at PH 9 and EC 4 so may not be an accurate reading. Good Luck!