Just from your brief description I would guess you got curl from low ph I go from cutting so don't have the stem problem,i also lst ,as for feed I hand water whilst in veg with a 1.2-4 ec then drip every 3 hours for 5 mins when I flick to flower,flower ec 1.5 until last 3 weeks of flower with 1.8-2.0 ec and a 5.5 ph Barnys blue cheese seems to work from this , if your growing in slabs cut along the bottom helps with drainage doing this for me works and stops from getting to wet good luck oh yeah with Rockwood you get nute build ups so flush between feed changes gd luck bud it's all trial and error till you find what suits you and your system matey