MH bulb replacement

Slicktop · Jan 21, 2019

I run a MH and T-5 set up and was curious if MH bulbs need to be replaced every year. I have been replacing mine every year for over 10 years but after seeing BRS video on T-5's pars after a year I was wondering if the same applied to a Radium 20k MH bulb. I only run 4 hours a day. I have read that its the daily on and off that ages the bulbs. My current bulb has been going 13 months.

Montiman · Jan 21, 2019

I have been curious of this as well. My understanding is that on Metal halide bulbs the bulb and ballast combo affects lamp life much more than on t5s.

Slicktop · Jan 21, 2019

I have an electronic ballast, not sure if that matters when it comes to the life of a MH bulb. I recently purchased some frags, need to mount and then I will make the change. I am not sure if anyone has done the research on MH bulbs like BRS did on T-5's.

jda · Jan 21, 2019

I would replace a 20K Radium at a year if you run it for 8-10 hours a day. At four hours, use it another year. It is time that the bulb was running, not calendar time.

Slicktop · Jan 21, 2019

Thanks, so the number of times a mh bulb is fired does not affect the bulbs par output? I heard it does but have no clue and don't have access to a par meter.

jda · Jan 21, 2019

I would not sweat this for how we use them. Keep in mind that your bulb can probably run for 10 years at 8-10 hours a day before it burns out... and you are using it for 1/10th of that time. The spectrum will shift and the output will reduce the longer that it runs, but we just use the cream out of them and replace them long before they really start to degrade.

I use 14k Phoenix for 24 months and I cannot tell when I replace them - this is the true sign. There is more output with the new ones, but the color is no different and the coral don't get mad at all. I do change my 20k Radiums at a year.

vanpire · Jan 21, 2019

I replaced my Radium after 2 years running it at 11 hours a day because I forgot to change it sooner. I shoot for 18 months. The reason I remembered to change the bulbs was that I noticed my corals started growing slower. Nothing bad. They were just growing slower.

I have my XM 10K for 4 years, and it can still beat the pants off my brand new radiums for coral growth though. It is the only bulb that makes my Oregon Tort grows somewhat quickly. Under Radiums, my Oregon Tort grows slowly. I wish they still made XMs. I have only one bulb left and I think it needs to be retired soon.

I run mine on electronic ballasts on the HQI mode, even for the XM SE Bulb.