is your ppm dropping at all? i can't imagine you aren't burning those smaller plants at that ppm level.
If you're running DWC you might as well do a proper feed chart up...always take daily readings and keep records. Feed chart history is super handy for future grows.
I would go by what the plant says it wants. Start by underfeeding and work your nutes up until you start breaking even with the PPM. Also do you feed daily? as in no RO watering on off days? It's important to get to a stage where you only give it plain RO if you stuffed up by overfeeding and need to flush. I actually dump my whole res when that happens but I can go four weeks without a res change, all the while PPM avg of 350-400 the entire time on my current grow.
growdiaries.com
If you use fulvic acid along with the humic and kelp, it will buffer your solution. I only check pH every off day...I've gone a week without checking it and only a .2 drift from 5.9 to 6.1
what is the ppm doing: same, rise or fall for the last week @ your 780 level.
one of the problems you are going to have is that all those plants are such different sizes. that tiny little one probably only needs 200 ppm, the biggest one might need 400 pp
Hmm well if your using tap water I highly recommend using amino acids. It will actually make the calcium in the water soluble for the plants to eat. Normally it's in the form of limescale and gypsum. This will effectively drop the tap water ppm by over 100 as that Ca becomes food for the plant. If you're looking for immediate results. Foliar feed with a weak kelp solution. Leaves take in nutrients way more effectively than at the root zone. Plus you will get the stress coping benefits from the kelp right away, you could even mix an all in one fert with it. 2ml/l of kelp 1ml/l of all in one fert.
make sure you top feed with the new nutes/hydroguard. you want to make sure you get the hydroguard into everywhere. from the stem, thru the hydroton, etc. take like a gallon jug, scoop out some res water, and dump it into every net pot.
