I agree with @OGIncognito observation and plan
I learned from the best! 
All those other great mods 
A lot of soils will buffer ph down to 5.8. That’s pretty normal. Your input is the important part. Which is where it should be. It looks to be a severe magnesium deficiency. Also a 20 hour light cycle with a scorpion should never be necessary. That will also add to the need for magnesium.
Would you dial back to a 18/6?
YES!!! 18/6.I run mine on this cycle from seed to finish with autos. They all have individual needs like sisters same parents but all different.
Have you flushed and reset? If growing non organic I flush whenever I see leaves change. Then a good feeding. Always does me right. The peeps above have u pointed right. Stay around 6.5 if you can and try keeping ur plants around 1000ish pmm. They need much less food then most give.