Yellow leaf tips

Could possibility be a PH issues. 6.7 is high for Hydro and just inside the ideal range for soil. You have two grows one soil one hydro. I would aim for aorund 5.8-5.9PH in veg and then boost it up to 6.2-6.3 in flower for a hydro setup. For a soil grow I would aim for aorund 6.5 in veg and then go up to 6.8 in flower. With no diary linked and no idea what your feeding or how much its hard to tell. Best to link your diary and post how much your feeding them in it, when I look at yours I don't see any feeding charts. Providing people with the info at their fingertips will help them give you a more rounded out answers. Blind guess, Potassium? Good Luck!

400ppm mis is probably a bit low. https://manicbotanix.com/calculators/ppm-in-solution-calc.php at least one time or anytime there is a drastic change that warrants it, you should have a gist of what your mix ppm is per molecule as well as in total. This will help you deduce what the problem is or if something is locking another molecules out etc etc.. at 400ppm it'd be really hard for this to be lockout. i'd wager any deficiency on a leaf symptom chart that matches up is probably right... but do the math and ensure nothing is odd.. you can compare to any recent diary i have and each N/P/K et al ppms are worked out. My Ca/Mg and S may be different due to different tap water, so YMMV on those, but the primaries should be pretty similar. N 120-130 P 50ish K 190-210? somewhere in that range likely. i run a little lower pH, so that will cause some variations too, but it's a good ballpark to compare to on your way to finding a proper balance in your garden for your environmental variables that inevitably differ from mine. e.g. you may be fine with slightly less N than me because N is more readily available at your pH compared to mine. my mix is 667 ppm or a bit over 1.3EC. I am soilless... 1.3-1.5 and below should be a safe area to roam. if i ran autos, i'd probably stick to 1.2-1.3 range. rarely have i seen one get too dark from my mix, but i also don't run autos very often or likely ever again lol.