How often would you reconmend replacing my 250w HQI DE MH Lamps? Recently one of 10k MH bulbs started flickering like a disco light, so I went to get a replacement at AO. They only had Reeflux 12k's, so thats what I got. After a few weeks I could stand the look of two 10k bubs on the left and right and a 12k bulb in the center. So I order 2 more Reeflux 12k bulbs. I just installed them, I am happy with the way the tank looks now, even though it is far less bright with the 12k's. Anyway, the two Current USA 10k's that I had been using are about 9 months old, used on average of about 6 hours a day. Thats only 1620 hours. The manufacturer claims these bulbs do not start to lose their effectiveness until about 5000 hours. Thats about 21 months at 8 hours a day. So I really dont how much life they have left in them, but if anyone wants them just let me know.