Sorry, pm's are disabled. I'm told it's usually a nutrient problem (deficiency of Mg?), most likely from improper pH. I suggest you get a pH meter or test kit, test your water before you use it, then test the runoff collected afterwards. Both should be around 6.5, slightly acidic. If its any different you should flush the soil with lots of pH balanced water and recheck. Do a search on the forums, there's literally dozens of people asking the same question and many more people answering them so you can take the general concensus. Hope this helps.

Post #420!