LOWERED LIGHTS TO 9 INCHES FROM TOP FROM MFGRS SUG...

First of all 18 inches is extremely high especially for those "Blurple" LED lights! 9 inch sounds more likely but it's still hard to know without a proper PPFD or umol/sqm reading, those are usually found on the lighting description when you search it up online - recommended amount for cannabis is about 700-900 without using Co2. For this grow it's too late but I'd suggest to ditch those "Bulrple" lights and go with proper LED lighting with broad spectrum and good color temps (Samsung Lm301H/B diode based lighting would be a good option). Now after that you lowered the lights just give the plants some time to fatten up and harvest. Did you defoliate the plants during flowering?? your plants barely have any fan leaves which are crucial for plant and bud development!! What is your irrigation schedule? how much do you irrigate? and do you use any other fertilizers other than the "Big Bloom"? your plants are showing signs of water damage (wilting foliage), and by using just that fertilizer you limit the nutrients your plants uptake (plants need all nutrients throughout the whole grow but in different ratios). If you could upload a picture under normal lighting that'll be great to further determine your plants health. Hope this helps! Good luck and happy growing :)