Liquid I had the same problem with my well water and you can't stay ahead of it--don't know but there are alkalines etc that will keep your ph from staying stable. RO water solved my problem and believe me I tried EVERYTHING before I started using it. Distilled water will work too and I know there are others out there with other suggestions for pure water. You can keep fighting it but I think you're going to have to go that route. Solved my problem 100% and not only do my plants love it my tropical fish do too. Also I would wonder if your light is a little too close for that young age--I'd have it more like two feet for awhile.
Weedhound Reviewed by Weedhound on . Yellow brown spots on leaves... This is a shot I took two days ago of a plant. Upon a friend's recommendation, I ceased using my nute program and dumped my solution entirely, using only water and hygrozyme, ph'ed to 5.7. Now, some more spots started appearing on one of the newer leaves yesterday, just isn't as full-spread as this one was (this is on the first true set of leaves). I'll try and give as much info as possible. Room is kept 74-77 degrees at all times, plenty of air circulation, humidity is 55-59%. Light is Rating: 5