Well this is tricky but i seen it before. Few things first, canna and biobizz are way low on cal/mag, canna actually expects you to ppm your water to 200ppm to allow sufficient calcium and magnesium before adding ferts, i hope you got a ppm meter or know the ppm of your water even better the cal ppm and mag ppm.
Plants look good in veg and then go crap for flowering??????
To me it definatly seems like a nute issue, raising the nutes wont work without the right cal/mag first and heat problems make the whole deal worse.
Doubt anyones got a quick fix but if we all work through the obvious first then i'm sure we will get there, well hopefully!lol!
Get back with these details, even if you know wether the water you are using is hard or soft. I know some are saying raise the ferts and some are saying its not a cal/mag deficiency but lets do it by the numbers.
On a bad note the plants dont look good dude but quite often it is a simple problem. Fert companies should specify things like water ppm in big bold letters. I run biobizz grow and bloom and need at least 80ppm calcium and 25ppm magnesium, now and again i need an extra dose of mag like when the plants start to flower and later on in flowering after a few weeks.
Sometimes its just a matter of the right water and right temps, simple things often overlooked. Peace