Nutrient deficiency?

High, The plant is eating her reserve nutrients from her leaves. Look at my Blue Hash diarie, I have been flushing and only give her plain water the last 2 weeks and she got the same colours as yours is showing now. So we know that she is using reserves so that means that they got a nutrient lockout. The cause of this deficiency could be pH issues or overfeeding. They both cause nutrient lockout but in this case it is the type of nutrients that you give her. You need nutrients for blooming from the moment that you see the first signs of flowering. Nutrients for blooming contain more phosphorus and potassium than nitrogen. Phosphorus plays a major role in the plants breathing and is essential for flower formation. But for now you can fix the dificiency and nutrient lockout problems with a good flush of your soil and I will explain you how you can do that the best. You can do this flushing by slowly pour water pH 6.2 onto the top of the soil, allowing it to drain freely from the bottom of the pot. Pour slowly, so the water doesn't overflow from the top of the pot. Use approximately four times the pot's volume in water to flush the soil. For example, use 1 gallon of water for a 1 quart pot. After the flushing you need to let the soil (almost) dry out completely. Then give nutrients for blooming. I really do like Plagron terra bloom together with green sensation and sugar royal. These product help you and your plant create big, fat and juicy buds! Happy Growing! 😋

Beautiful colors! https://www.growweedeasy.com/cannabis-symptoms-pictures

15/30/15 is really not that suitable for cannabis, way too much posphorous and a bit strong on the nitrogen and potassium. For flowering you need something more like 4/4/6.

The purple is either genetics or your pH is off. So, check your pH. If it is good(6.0-6.8), the color is genetics. As far as the burned tips of the leaves, that's most likely nutrient burn. Water, with pH'ed water only, for a week or so. It should clear up, as well. I hope this helps.

If you're feeding 15-30-15, it's probably got far too much nitrogen... in flower, you want a ratio of 1-2-3. Excess nitrogen will lockout other nutrients and this is what is happening now. You should do a flush (3 gallons of pH'd water for every gallon of pot size) and let her dry out. When you start your nutes again, you need to find nutes that are much lower in nitrogen (but not lacking it completely!). PH is also of prime concern - make sure it sits at about 6.2 but anywhere between 6.0 and 6.5 is fine. Finally, don't adhere to such a regimented schedule of X amount every X days... you've got to let the plant tell you when it needs something... only give it something when the pot is dry - and practice the water/feed/water/feed routine and things should be fine. Good luck!

Apart from the slightly burned tips, I don't really see much wrong here. If your "Night" temp (when the lights are off) dips between 65 - 70F (18 - 21C), the slight stress can cause the plant to express latent pigmentation. Most of the time, this appears in the buds, but I've seen it appear in the stems (separate from red stems during veg or whatever), leaves, even in the trichromes. If the plants are still growing well, and especially if this is a strain known for coloration, I wouldn't worry too much about it.