Checked all the basics !? PH, knewt possibilities. So get this, in doing so, I noticed the yellowing of slow sis was in just the spot where i placed a (cheaper) LED lamp pointing up to help lower Colas grow. Wondering, i changed rotation of girl like normal. And w/in 2 days, same yellowing from exposure! Even tho it was meant as emergency backup, shows spend the extra $ for quality. Or you can have situatons avoidable. 😅