no mate , coco fibre is probably one of the most stable mediums u'll get , it has a netural ph , it hold moisture very well but also it is very light and airy , mixed to a 50/50 mix u get a good medium that drains very well , which inturn helps oxygen get to the roots. i only ever flush when i do my last watering ( sorry i forgot to mention with about 2 weeks to go i use GH ripen formula for 10 days ) and the i put the plant into the dark for 7 days just to finish it. if u look ay my plants i am sure u'll agree they are very healthy . the biggest + point over hydro is that for sum reason u make a mistake, with coco fibre all u have to so is give the plant a good flush , with hydro by the time u notice sumthing is going wrong its normally way too late.