My plant is about 2 months into flower. its in a 5 gal bucket using FF nutes. I flushed it last week for 4 days with 4 gallons of just water. when i was done with the flush, the plant looked a little stressed and showed a little yellowing. Now I have it back on its nutes but the fan leaves on top stayed yellow and a few have gone yellow since. I know yellowing from the bottom in a normal process during flowering and before the flush it was yellowing from only the bottom so i figured it was normal, but now its starting to worry me a little. any suggestions?
That all-over leaf yellowing is from Nitrogen deficiency. Be careful not to overdo it when adding more N- they'll need less later in flowering.