Hydroponic Roots Question

when i grow in dwc i use rock wool cubes. i set my water up like this, when the root starts to come out from the bottom, you want your water to be a few inches away from the cube and the root, reason is that root will stretch until it hits the water, i use a clonex and water solution in the water as that is good for the roots, the first few weeks of dwc are the most important as you want to grow the roots, the gap i talked about needs to be there as the bubble make oxygen in this area and the roots suck it up, you do not want water all the way to the top or you will have slow growth and you will wonder what your doing wrong. with dwc you also want to make sure you use a dark air line or cover it up if it is clear, i mean cover the tube that is exposed to light, by keeping the air tube covered if it is clear helps keep algae away from forming inside the air tube, this in turn prevent root problems later. also when you do add nutrients i would suggest using a all purpose fertilizer like 20-20-20 through the whole veg grow, i suggest this as it has worked very well for me in dwc as this mix has macro nutrients in it. you will need to be on top of your ph and you want to check it daily as the ph will drop over night. also i suggest having an extra bucket that you keep clean and have it filled with water. let the water sit 24 hours before adding any nutrients. so when you do change your bucket to clean, you have a clean one waiting and you just add your air stone and nutrients and then the plant. keep your ph between a 5,6-6.2 the sweet spot is 5.8-6 ph. if you need more help just let me know. happy growing and hope this helps