Hello kushgoddess,
Check your power draw.
In my lab I use a kilawatt meter to measure the efficiency of bulbs. Bulbs seem to pull power in accordance to what they can handle. If your 600 is drawing less than 500 its running less than 85% efficiency.
Dailedin Reviewed by Dailedin on . Lumen tester readings Hi there, Although I am not a newbie cultivator, I am new to this site and new to using a lumen tester. I have browsed every site imaginable to try and decode this lumen testing issue. My lights I believe are 2 years and older (600 watt Gavitas) and I say "I believe" because I sort of "adopted" this farm and I have been here close to 2 years. I have heard conflicting stories from many old school cultivators in the area. Some say they've run these same lights for 3 years and still have great Rating: 5