LED Grow update no.18, January 12th, 2011 Taken from "indoor growing", "testing the pro-grow 260 LED light" Hey all, So over the past 2 days I have noticed one of the plants showing a deficiency. To me it looks like a magnesium issue. I gave that plant an extra feeding of bat guano and some seaweed and tomato fertiliser. I mixed a heaped tea spoon of bat guano in warm/hot water and mixed it well. However, this extra feeding did not seem to fix the problem. I did some reading on the subject and I cane to the conclusion that it might be that the magnesium is being locked out. Locked out meaning that the plant roots can no longer access the magnesium in the soil due to other issues. The water in my area is very hard and this can cause issues with magnesium uptake, over time. Possibly the hard water has affected the soil to cause this. I went to the chemist and I bought some Epsom salts (magnesium sulphate) in an attempt to unlock the magnesium from the soil. I mixed one tea spoon with one gallon of water. I haven’t used all the water yet on this plant. I poured 1 litre of the Epsom salt water into the soil. You can see where I got this information on the home page of my grow journal blog. On the right hand side, where the links are, look for plants problems/disease. This is a very good link which shows many different plant problems and how to deal with them. LED Logger So I hope this will resolve my magnesium issue. It seemed strange that this plant was the only one affected. But then I remembered that this plant has been watered much more than the others as it was positioned under the fan. This extra watering, with hard water, could have caused this reaction. I believe it is the calcium in the drinking water which affects the soil. I will keep you updated on the recovery of this plant. It could be possible that I will have this issue with all the plants over the next few weeks. On my next grow I will have to get filtered water for the plants. Enjoy the pics. If anyone has other ideas as to what has happened to this one plant I would like to hear it. I'm not a pro grower so advice would be great.