First run on Coco.. and killing my plants..; help please

well you say 70/30 coco+perlite here and diary says soil... if it is coco, treat it as such... if you are treating it like soil, just use a soil. mixing soilless and soil methods is not helpful.

nitrogen deficiency. How you should treat a soilless substrate: Fertigation - everytime. 1.3-1.5EC overall concentration not counting your tap water. Ratio of nutes is as important as overall concentration. Also a pH somehwere near 6 - jsut be consistent about it. Proper soilless/hydro fertilizers should ph-balance and ph-buffer on its own, but some cheap shoddily-made shit will not. Always get 10% runoff waste water -- fine for plants in the earth but don't pour on any potted plants, or toss down the drain. Wait for top layer to start to dry and repeat. Deviating from this procedure is doing it wrong. the amount of dryback between irrigations is up to you as long as it's at least 33%. that should avoid root-rot. use an app to calculate ppms from your guaranteed analysis labels... shoot for something near: 120-130 N 40-60 P 180ish K 100+ Ca 75ish Mg 100+ S These will vary a bit due to local temp/rh (VPD) and also your tap water, but it's a ballpark starting point that will take minimal adjustment based on what you see. This is a low starting concentration, so more often you'll need to amp up slightly (5-10%) unless you run a higher VPD like me (not on purpose, not a suggestion). It's good to start a bit on low side -- much easier to add than to take away from substrate. This well-balanced diet along with the 10% runoff will result in a consistent nutrient level around the roots at all times. This means you don't have to worry about buildup occuring. You can still overfeed a plant, though. it just won't be caused by a buildup in the soil.. it'll be because your formula is providing too much of that particular nute -- simply adjust formula and it'll correct itself over time.