went in the grow room this morning and the plants had lost there vigour and some of the leaves have gone yellow and droopy, im using a dwc system ,its not root rott as i have had that before and know the signs,i have had fresh water in the res for the last 3-4 days to give them a flush and they looked great but now a day after i have put some nutrients in they are starting to look ill again,just added some revive .........just wondered if anyone has used it andhow they got on ?