There are many strong purple varieties just like there are many weak green strains and vice
versa. check out the list of purple I made in the middle somewhere and pick some out and
locate them on IC.
Yes dropping the temps during flowering is a bad idea. you should try and keep the temperatures
constant. I made the same mistake last year when the lights go out and the plants get cold
condense water settles in the buds when the lights come on again warming the flowers and
causing bud rot.
If it was outside then conditions would make it harder for mould to form.