Lower Growing Shoots are yellowing

A few days ago my leaves started turning very dark green,
so I misted them with Copper, and flushed the soil to get rid of a possible N over-fert.

However today I started noticing the lower leaves getting quite light green,
and the bottom growing shoots started getting yellow to white, with the tip burning.

I considered that maybe the lighting wasnt too proper, iluminating to little the bottom of the plant, and have just fixed that, but could it be that i took too much of the nutrients out in the flush?

much thx!

probably n overdose...keep flushing for a few waterings. that can cause a few other problems that may look like other deficincies but its probably excess nitrogen locking other nutrients out. flush and watch your ph.