Please, remember (and this applys to ANYONE!) that my advice is well meant but that I am at a newbie level. With that out of the way..... If you were having problems with overfeeding, and it sounds like you were using chems, you might have gotten a build up of deposits in your medium. I don't know what your using but I'm pretty sure it can happen in any of them. Maybe you should flush your medium and continue with a diluted feed like bonbon said. (Hi Bonbon!) PLEASE look around for methods first before you try it as I have'nt been there yet...... If you ARE using chems then the maker probably gave you directions for flushing w/ your nutes. That alone kind of tells you something, huh? Maybe now would be a good time to GO ORGANIC.........