My clones are yellowing and dying

IMHO they need more oxigen

How often do you feed them? and with what? Just water and Clonex? I never used spray, but I used to just mist them with water, Other then that, during the planting of the cuttings the plugs would have been soaked in nutrients for 24 hours, and after that I would not feed them for at least a few days, usually only twice before they are ready (10-12 days) I think I used similar (brown) plugs, but you will have to figure out by experience how much your plugs can hold. Put the bottom of the plug against your cheek, and if it's moist your good.. They need to work in order to grow roots, over doing it with water can really damage the cuttings. And misting once a day to keep the moist/humidity up. Watering by soaking the whole tray of plugs into another tray for like 20 seconds. I kept these in closed of boxes by the way, trying to keep the humidity high.