Hello all! I have looked and looked and can't find a definitive answer. From your experience, how often do you change your HPS bulbs? I have used the same bulb for 2 grows. It was a cheap Plantmax bulb. I run small grows. (4-6 soil plants in a tent with CO2) Is there a decent return on investment in a better bulb? Hortilux is $100+ The 400W Sylvania bulb at Home Depot is $18. Any advice would help. I'm going to buy another bulb. You almost always get what you pay for. Is it true here? Thanks in advance!