I just did some light meter testing with a 1000w Hortilux bulb and Micromole ballast combo and the lumens per watt actually dropped when overdriven to 1150w. The lux was 11% higher at 1150w compared to 1000w. 1000w was the most efficient setting, with 850w slightly more efficient than 1150w, and 600w the least efficient. (no surprise there at least) I don't have equipment to test PAR though.
Oddly enough, testing the same spot with the same reflector, a Quantum 600w ballast with a 600w Ushio HPS bulb scored over 10% higher per watt than all the Micromole+Hortilux settings. The Ushio is new and the Hortilux has had about 500 hours of use.
I should re-test everything at all corners and center of the tent, as this result may be because of a different light spread. The size of the bulb may be giving a misleading result due to a different reflective pattern.
Oddly enough, testing the same spot with the same reflector, a Quantum 600w ballast with a 600w Ushio HPS bulb scored over 10% higher per watt than all the Micromole+Hortilux settings. The Ushio is new and the Hortilux has had about 500 hours of use.
I should re-test everything at all corners and center of the tent, as this result may be because of a different light spread. The size of the bulb may be giving a misleading result due to a different reflective pattern.