My 3 week old Durban Poison, grown from feminized seeds has suddenly started displaying curled leaves and rusty brown spots. They are planted temporarily in 3 gallon fabric pots, previously in solo cups. The soil is Pro-Mix Organic potting soil. It does have a slow release organic fertilizer. I watered them 2 days ago with 2 liters of 6.5 ph water each. I'm not sure if this is a sign of over watering or nutrient deficiency , or both? I've never used this version of Pro-Mix before. I was planning of eventually top dressing them with Gaia Green All Purpose and Worm Castings. My grow tent is 80 degrees F, with a humidity of 60%. My other plants are not displaying this problem. Thanks for any insight!