I generally use 3 teaspoons per gallon.But not sure if what I'm seeing in that pic is a Mg def. Little more info on your setup and water/feeding times would help. I believe a Mg def starts more towards the upper leaves not lower.
I thought that when the plants required Mg, that the tips of the leaves pointed up. Many refer to this as the plant, "praying for Mg". I would like to see other opinions on this. Mg may not be what they need.
i am a first timer, i built up 5 rumple buckets, i bought the same RO rumple uses, bought 3 part GH but am only using gc flora and micro in a lucas formula. my girl drinks like a fish and i have to add back like 1-1.5 gallons a day of either ph corrected water if the ph drops and the ec goes up or full strength lucas (1.8 1.9 ec) if the ph rises and the ec goes down.. growin under a 600w hps. i had her under 1000w metal halide all by herself for like 2 months and some. i have been having this problem all along. seriously. people have been telling me im either not using enough food or that i need to add some magnesium. my ec does shoot up pretty high (2.2 2.3) but never for very long, as i have nothing else to do but to tend to my plant.
not sure if itll help to know but shes a greenhouse femmed white rhino 11 days into flower. i have problems believing that this plant is actually a white rhino. even tho it came from the doc with the breeders pack. but then again i find this all very hard to believe. ill go get a ec ph reading right now. notice the tips of the leaves pointing down slightly.