Nutrient problem following increasing CO2

I recently increased CO2 to 800 ppm. I've used much higher levels in the past, but this time, an apparent magnesium deficiency developed almost immediately. My first theory was the increased transpiration caused the plant to pull up a nutrient that blocked the magnesium. But magnesium is mobile, so I'm not sure. Anyone ever experience something like this before - a magnesium deficiency occurring following a rapid increase in CO2? I've attached a photo of the leaf.

i'm pretty sure that's not low Mg. Hard to tell from one leaf but it looks like low Boron and I've had it a couple times. A little boric acid from the drug store fixed mine up PDQ. One dose of a tsp/gal worked.

Toxic salts buildup can burn leaves too but takes a while and tends to start on leaf edges first like nutrient burn but can be across the leaf surface turning them yellow/orange/brown and makes the leves thick and crispy dry. Happens to me easily due to very low humidity so the plants transpire excessively drawing up way more nutes than they can use that build up in the leaves. Usually starts showing in mid-flower on older fan leaves and can get bad fast. Can start on top leaves first if there is excess radiant heat and those leaves will generally start going 'taco' first. 'Canoe' for us Canucks.






Hope that helps.