possible lock out or mag issue?

Hey there Bucketman, you're absolutely right , it's a magnesium defficiency. yiu can tell by the yellowing on the serrated edges of the leafs . All you gotta do is add cal mag if you're not already doing that . if you are , the plant's not absorbing it quick enough, so what you want to do is add it as a spray and spray at lights on . Absorption through the leafs is 80% efficient and through the roots is 20% efficient. so that's why it can really help stop the spread of this kind of issue. Grab some calmag and the plant should fully recover in 10 days or less. Hope this helps ! 🚀

If you haven't been using cal/mg then you need to add some once or twice a week. 100 ppm. that gets added to your total ec. Cheers