thanks all for the great advise if i bring the ppm dowd to 400 will that shock them? i have a bottle of floracleen by g.h. but it says only use it 4hrs then drain and put new nute's in.. now when i flush with floracleen can i leave that floracleen in there overnite without hurting anything or do the 4hr deal? one said leave the cal-mag for awhile. i was using alittle of liq karma is that a good thing to use? sorry for all the Q'S.. thanks