Howdy TheBanzo, I have been growing (10 successful grows) using four 55 watt (250 watt equivalent), mixed 50/50 of 2700° K and 5000° K bulbs, for each of my planters. For grow number 11, I have upgraded my lamps to use sixteen 23 watt (100 watt equivalent, mixed colors ) bulbs with four 20 watt UV bulbs. The main reason for the change was to increase the total wattage (from 220 watts to 480 watts), and the UV for an increase of turpene production. The 55 watt bulbs were getting more difficult to find and they were getting more costly as well. The 55 watt bulbs were costing approximately 29 cents per watt as compared to only 13.5 cents per watt for the 23 watt bulbs (accept for the UV bulbs).