After 7 weeks of flowering, the tips of my leaves started to turn purple, what kind of deficiency is bothering them? Pk? I use canna cocos and there Pk is

Normally purple leaves come with either genetics, a phosphorus defficiency or low temperatures. If purple leaves are uncommon with that genetics, the remaining factors are either temperature or phosphorus defficiency... what are your night and day time temperatures? If they are too below 19º it could be because of the temperature, but that would not be something to really worry about. Check your temps, if they are within the 18~26 degrees celcius, bump the phosphorus a little bit on the next feed. Happy growing mate

Sorry BansjeeGT is correct. Phosphorus not potassium deficiency if it is a deficiency, but I still think it's nothing to worry about this close. Anything added will take a week to show improvement and you're getting to the end of the grow now.

Purple is a phosphorus def, but in that week can be normal she is close, but also check your night temperature, by lower temp plant change colours to get diffrent spectrum of light, antifrozen mechanic