Yellowing leaves & tips curling down on 14th day. Coco / Autopot / Hesi / Mars Hydro fc-1500

hours of light in itself is only half the equation. Rate of photons x hours = light applied, and DLI takes it a step further making it relative to a m^2 space so that you can compare apples to apples across different sized gardens. you want to shoot for 35-40 dli in ambient CO2 conditions. Only if you light is very weak should you run it 24/0 and be gauranteed it overcomes any negative of eliminating a dark cycle, otherwise keep at least a 6 hour dark cycle. I would weigh ekeing out the maximum DLI you can provide (trial and error to find that value) over a dark cycle, but should be avoided. Dark cycle processes can and do take place in the light, so it's not "do or die". I'd bet the house "max" dli is more important, if you have to sacrifice something. If growing photoperiods and only 1 light, it's wise to make sure that light can cover the full area with enough light proportional to change of hours at flip. e.g. 18 to 12 hours would be 67% power in vege, then 100% power in flower. 16/8 to 12/12 would be 75% in vege and 100% in flower. This way you know you are providing the same 'max' DLI target, which is what matters. local variables in addition to ambient co2 will make your 'max' DLI slightly different from someone else's. A proper VPD will definitely make your plants more receptive and capable of greater amounts of photosynthesis per day, therefore will generally handle more light per day, limited by co2 conditions. autopots are a bottom up watering system? blech... you'll always have to worry about buildup at top of where it gets moist. Takes the most important element of soilless growing and throws it out the window - 10% drain to waste. It's what makes soilless growing so easy. That coco has zero drainage elements added, so it's less than optimal for frequent irrigations. Use 2:1 perlite or similar, so 33% of volume should be drainage amendments with coco and 50% with sphagnum peat moss, a superior option for soilless. Might be why your plants have a little droop, too, but more than 1 thing can cause that. I'd still stick to a pronounced wet-dry cycle early on and if you want to do more frequent fertigations after the root mass has developed and the plant can drink fast enough to warrant it, go for that heading into flower. plant size and pot size have to jive for that to work out well. Want at least a 33% loss of water weight between 'frequient' fertigations.