Mostly all of my plants either have or are developing a yellow tint on the leaves and they are getting these brown spots. These are indoor grown white widow seedlings, I have been using rain water to water them and haven't been testing PH, they are planted in Fox Farm ocean forest soil, and I have not been adding any nutrients. I have asked a few different people and they all gave me different answers but from photos I have looked at online it looked similar to PH spots. This is my first time growing. Please help! Thanksss!!!