Hey there Chris, great job on those strawberries, the good news is they're not really turning purple like they would during the cold or if they had colors. the discoloration on the leaf tips is from slight nutrient burn and on the sides it's from slight potassium excess as well as a bit of magnesium deficiency. The purple color on the frost on the leafs is actually from the trichomes ripening and oxidizing. Best thing you can do is pull back 0.2-0.4 mL/L on the feeds and maintain this level as well as reduce your light cycle by a couple hours to relieve the pressure on the Mg. Dont sweat it , looks great. Hope this helps ! 🚀