After battling this assumed cal-mag issue, I'm now pretty sure that the problem is actually a Phosphorus deficiency. It only began during flower and that should probably have been an indicator. I guess I was confused as the issue also presented itself after switching to RO so i assumed cal-mag was the culprit but I think that was just chance as I happened to make the switch as flower began.
Shouldn't have run the feed so low I guess. I'd been struggling to get the ppm down due to the high ppm of the plant magic cal-mag and focusing too much on that, not enough on what the plants were telling me.
The switch to vitalink has allowed me 'space' in the ppms to run the feed at pretty much full strength, so I'm gonna up it a bit and follow my gut a little more. Had my nose in books when it should have been in the tent.
All that said, i could be wrong and it's still just a calcium issue. Guess we'll find out.
Wish me luck! I think it might be too late for the NYCD, I'll give a little longer to see if there's any recovery but otherwise I'll cull her and give the space over to the other plants in there. I have a skunk at day 22, a Critical Kush which has just popped above ground and a White Chem (courtesy of my growbro
@Froot n Fuel) about to go in, along with the Zkittlez which is maybe like 3 weeks from harvest, I wouldn't feel too awful about losing the NYCD. Still got another couple of seeds so she can get another chance to shine in the next run.