what kind of water are you using and how old are your plants?

If your using R/o water, then you need to add some calmag+
dusto2k3 Reviewed by dusto2k3 on . Magnesium Deficiency? Hey everyone, been looking at my plants lately and they seem to be yellowing a little like a magnesium deficiency, got some pics for you all to see. Pic 1 is my 3 week old plant but I think it is also overwatered. Pic 2 is my 8 week old plant with clear yellowing in the middle. Pic 3 is my other 8 week old plant which seems to be affected the worst. Pic 4 is a close up and comparision of the 2 different leaves, The yellowing seems to be only on the new leaf sets. Rating: 5