gezzer that is also what a local greenhouse man( he ownes it, aslo I know that dont mean a lot but he seem to have his ship togeter* we were talkin about tomatos.. with a smile on his face) said so, they get some warmth from the lights, it warms them. puttin room temp or cooler water on them cools them signifigantly... and they then can focus on roots and absorbtion durring lights out. because he said sudden temp changes can effect a plants matabolisim i know my spellin stinks so please laughin is cool im not stupid just suck at typin and dont care... love ya