no problems here except for the Ph shifts. I stopped trying to fight water temp problems and have learned two things that work for me to prevent root rot. One is to use only non-organic based hydro nutrients and other thing is do not break any roots, especially during transplant from my mini dwc...
http://www.alita.com/ or similar style of air pump not cheap but gets the job done. I got the AL-60 running 16 med ecoplus air stones with plenty of air to spare.
For med/big systems get a Alita air pump or similar brand. They aren't cheap but flat out the best for the job. I got the AL-60 running 6 15 ga. tubs with 4 ecoplus med. sized round air stones per tub no problem.