Are MH and HPS bulbs interchangeable?

Hello,

I recently bought a 400W HPS Ballast off of Craigslist, and was wondering if I could put a 400W Metal Halide bulb in it. I see that on ebay, some people are selling HPS/MH systems, but in the description, it says it is an HPS ballast, and includes a MH bulb. Are they interchangeable, or are these special ballasts? Or I suppose they could just be ripping people off. Thanks

S-Town

You buy a conversion bulb. So if you have an HPS ballast, you would use a regular HPS bulb, but a CONVERSION MH Bulb.

There are also ballasts that can auto-detect what is plugged in, and will run either HPS or MH. Thats what I use.

unless that ballast you bought is a digital one, putting a regular MH bulb in a HPS ballast will cause ugly things to happen. be warned that the conversion bulbs are pretty inefficient and put out much less light lumens wise than a regular HPS or MH would.

JohnnyPotSeed1969 said:

unless that ballast you bought is a digital one, putting a regular MH bulb in a HPS ballast will cause ugly things to happen. be warned that the conversion bulbs are pretty inefficient and put out much less light lumens wise than a regular HPS or MH would.

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Yeah i agree about the MH conversion bulbs being inefficient, I have one and im starting to believe it was a waste of money. But it will do as a back up untill my hps bulb gets back.