PPFD, man. Just use that Photone app for iOS. It's accurate enough for growing. For the diffuser, you can just cut a small blank portion of a grocery store receipt and place it over the front facing camera. Just turn off the oscillating fans so it doesn't blow off the phone/iPad.
What is your runoff EC? Never adjust your inflow EC without referencing your runoff EC.
Take a picture with the lights off using the flash from your phone or (room lighting) and you will see the leaves will likely be quite green. You can do that during their dark cycle if you want because it's in veg and doesn't matter if it gets briefly disrupted.
Also, you're letting your coco get too dry. You're starting to treat it like soil again by going by weight to feed. You can water coco to stay at pretty much 100% saturation and the roots will still get oxygen if the coco was prepped properly, you have proper drainage, and ensured that you won't have a stagnant spot in the center that can become hypoxic.
You're not feeding to give it more water; you can literally grow in coco like soil and water once or twice a week, but that's not optimal and using soil would work better if you're going to treat coco like it's soil.
You're feeding it at least once daily to keep the EC of the rhizosphere consistent and replenish the water with cool, fresh oxygenated water. You have to think of growing in coco like it's DWC. In DWC, the roots are 100% in water at all times.
With regard to your question about runoff in your other thread, you can get as much runoff as you like, so long as it is at least 10%. Most people just prefer to cut down on waste by only giving it as much as is needed to maintain a consistent rhizosphere.
If one is fertigating once a day, more runoff is needed to maintain a consistent rhizosphere; if one is fertigating six times a day, then less runoff is needed to maintain a consistent rhizosphere, but in either case, at least 10%.
