Hello, here’s my problem… my plants are well into the flowering stage. I decided yesterday, following my instruction manual, to switch them from blue/red lights to simply red (bloom) to promote the flowering process. However, within 24 hours, several of my plants have leaves that are yellowing and curling up… I’d like to know if this is normal for them to change so drastically in such a short time, after only 14 hours of exposure. I haven’t adjusted the height of my lights… should the lights be higher? Should I switch back to blue/red? Should I water more or less? Do they need specific nutrients at this last stage? But also, and most importantly… should I cut off the dry yellow leaves? Thanks for your feedback 
Hi, first, are you in soil? Or something else? Especially monitor your pH and EC. Do you take readings of the runoff water from your pots? This can also give you information on whether there might have been an accumulation of salts there; in that case, it gives you clues. The slightly wilted leaf shape suggests not enough water, and the color, depending on if they start from the plant downwards (excess nutrients) or from the bottom upwards (rather a deficiency).
Pictures would be helpful for more accurate diagnoses.