Thanks for suggesting the ph...all I can say is that my ph levels have read 5.8 - 6.0 max for the last two weeks consistently, which is why I thought it was nuteburn...just noticed that some roots actually made it into the NFT reservoir...while this happened last time I had a (happily trouble-free, wildly successful) micro-grow, it didn't happen until they were way into flowering mode...any thoughts on roots in the tanks?
best,
jash