i run kinda a cross,,dwc with a top feed,,3 gal buckets,,i was running into the same problim awile back & i solved it by dropping my water temps to arouns 68 f.i also lowered my water level to about 1 &1/2 inch of water in the bottem of my 3 gal buckets. plusi also use hygrozyeme,,,awsome stuff,,mana from heaven for root rot. before i forget,,,i also fill up oldmt dew bottels with tap water & fereeze them,i dont have the cash for a chiller & if yours isnt keeping up that might help to. peace bro.