How does a 150/175w MH ballast work?

[mtfinger22]

Long time lurker, first time poster.

I'm setting up a new tank and decided to go MH. I have noticed that a lot of electronic 150w ballasts are listed for 150/175.

How do these ballasts know what type of bulb you are putting on them? (They don't have a switch) Or do they not care and just under-drive a 175w bulb.

I'm looking to go 175w, but want to make sure I'm not underdriving them by using one of the 150/175 ballasts.

Thanks for any information!

 

[Krish]

Welcome to RF!!! :welcome:. You know, I've never noticed them using the same ballast for the 150/175w. . Here's a bump back to the top.


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[mtfinger22]

I have never noticed it before either, but now that I'm in the Market for MH, I'm seeing them everywhere. Multiple ballast companies list their 150w Electronic ballasts as 150w/175w. Galaxy (Sunlight Supply), CoralVue, ARO, etc.

I know that since they are listed that way, I'm sure they with "work", but I very curious if the ballast just "works" by underdriving the 175w bulbs or if there is some magic electronics in the ballast and bulbs that tells the ballast to drive 150s at 150w and 175 at 175w.

Anyone have any insight?

 

[Aquanaut]

If you can find a HQI ballast of equivelent wattage for your standard mogul single ended set-up, then you can effectively overdrive them. I am using 250W lamps in mogul Lumitek III housings and driving them w/HQI 250W ballasts. The output is near 400W intensity for less heat energy and increased par too. Seems to drive light deeper into the tank.