Ph problem, +Root rott???

Hi to all. Right then, Im growing in a nft tank using large rockwool slabs. Ive got 4 feemales that are 2.5 week's into flowering. They are under a 600w and a 400w hps lighting and are being fed on ionic bloom at 0.8 ec, (but im not using the boost as I have heard that it leaves its taste on the finished product.) I try to keep the ph on 5.8, but it allways goes up to about 6.8 in a matter of about 4 hours or so!!!. Also, parts of the roots seem to be changing colour from wight to cream. Is this the start of root rott?? and can this be the reasons of the ph problem. Any sugestions woul be greatly appriciated. :D

That is the reason why I no longer use rock wool....I hate that shit. Give them a flush with a good flushing chemical like the one GH makes or Advanced then start back with just Ph adjusted water and some H2o2 for a few day's. Then change again this time with your regular nutrients. The flusher and H2o2 will help if there is any nutrient lock caused by your problem. Hydroponics recovers fast so you should be ok

alright mate empty ur tank put fresh soulotion in with ec of 0.6 and a ph of 6 ok.then run ur pump faster than normal and leave it 4 3hours now empty ur tank again and fill up with water ph at6 and ur ec is where u want it.dont put ice cold water in ur tanks.dont use ur boster now only in week 4 or 5 u should be flushing 2 weeks before harvest. ur ec is wrong 2 low but u cant just top it up u must build up slowly 2weeks into flower u should be on 1.2 to 1.6 not 2 worry just do the first part wait few days u will see everythink will be cool.stay slippery dude