Ive got 2 strains going...both Clearwater Genetics...SUGAR RUSH(Indica) & WHITE HOT GUAVA(Sativa)
Both are turning Dark Purple !
My 5th grow since June of '18, when Oklahoma went Medical.
Never had one turn this dark purple before.
Genetics or too much light. This is the answer in almost every case of purpling.
Other possibility is if it gets very cold at times (like under 60°F).