I wish I knew

Probably the light.. QB needs to be more than 14" away. Was this a recent change? Did you amp up or get it closer anytime in the last 2-3 weeks? It can be 'too much' and tolerate it for a while in cases of providing a little too much instead of a lot too much, lol. Constantly droopy plants and stunted growth is a sure sign of too much light - one of multiple causes, so it takes a little cross-referencing to eliminate potential causes. could be watering habits over time too, based on the description here and the likely bad advice. Check out cocoforcannabis.com. Their guides and articles don't engage in bro science. They keep it simple and straight forward. It doesn't matter if it is coco coir or another option for soilless medium, it's the same dynamics. coco is not magic, nor special. It still needs a proper amount of perlite or similar to be the correct gas:water mixture in the pot and that can be achieved several ways with different solid mediums. Proper irrigation for soilless: 1) always fertigate and get 10% runoff, minimum. Runoff is essential. 2) wait for appropriate dryback and repeat. If you are choosing anything in a top-down way instead of allowing an observance to trigger a behaviour, you are doing it wrong. You give the volume of water it takes to get the job done with 10% runoff. If you trigger an irrigation based on sameloss of weight or samelevel of dryness up top, then it will be a similar volume you can predict. 10% runoff eliminates problems associated with buildup of nutesin the medium. This does not mean you cannot cause a toxicity by feeding too high of concentration, but it does eliminate a potential cause of such problems. With soiless/hydro context, all issues can be fixed by adjusting the formula. Unless it's a dumpster fire happening, there is never a need to flush. Flush is a last-ditch effort for major rootzone problems. Flushing is incredibly stressful for the plant and should only be done when absolutely necessary and not used as a security blanket to make someone feel better, which is often the case... I'd suggest something similar to the instructed outcome of J.R. Peter's Jacks 3-2-1 hydro 3-part setup. Similar ratios and then adjust overall concentration to what works long-term given your local variables. On top of varying genetics, plant matabolism is impacted by temp, rh, and co2 levels, so one garden is not exactly the same as another. Somewher ebetween 600-750ppm is probably a good amount for just about any garden, as long as it is well-balanced. That is based on calculation from gauranteed analysis lables and not some wonky, inaccurate TDS pen that converts EC to PPM in a highly inaccurate way -- i.e. there are 3 or 4 different conversion factors and the only reason your pen uses one or the other is the brand and region you bought it from. A potentially 40% different conversion value based on brand alone. one might read 600, and another 840 and it's the same fucking thing in reality, lol. There are free sites and apps that do this math for you. Some may even tabulate several products or allow you to type in targeted ppm of each nutrient and give a dosage to use of your products... it's not so hard to work that stuff out on your own, either. fertilization is best when you provide a consistent level of all the nutrients in a way that they do not impede each other. It's not about adding this in week 4 or that in week 8. It may require a shift as vege growth ends, but even that is mostly just drawing back and not playing mad scientist with the formula. it's not foie gras. Boosting 'something' doesn't make the plant metabolize any more than it could per day.. as long as it can meet needs, it's the 'right' amount and boosting is a marketing manipulation.