Are you using the drain to waste program. I run hempy with perlite and coco or vermiculite depending on the strain. I start with the chart from their website. I usually get some yellowing in the 5th or 6th week if im not running the 5, 5, 2.5ml per gal formula. I just run basic 3 part with Liquid cool bloom and floralicious plus which both stink to high hell. I forgot about it for an hour while it was mixing and it stunk the entire flower room up. I have almost no issues running this setup with basic nutes. Keep your PH at 6.0 to 6.5 and you should be good. Forgot to note that I flush after every 3rd watering. Usually when you have to switch up the nutes to suite your girls for blooming. I use about 2ml to 3ml per gal of flora kleen and ph the water and water them and let them go a couple of days(in hempy you water every 2 to 3 days when they are budding). This keeps nutes from building up in the media. I only had a couple of weak strains that did weird things and I just accepted it and moved onto more robust "super fire" strains.