I have attached equipment and it runs sodium lap fine. But mercury lamp only goes for a minute(I want a green light underwater for fish.) I hear the open voltage isn't enough. Any tips?

Thanks

My mercury is a new brinks 175W off Amazon.

since this ballast made for 55 arc volts.  it will cause Mercury lamp to cycle .  not staying lit.

So what ballast should I get? Do you have a link?

Thanks
Shane

I have looked for higher arc volt ballast but not sure what to get...

S56 HPS ballast is kinda rare it 100 arc volts
 but how ever You can still get same kinda ballast
in more common MH 150 watt and Still run S56 HPS
lamps on it.  but to answer the above question just Deactivate the ignitor as MV dont require to use it since
it use a starting probe to strike a lamp.  this is closest match to run MV.  also there Probe start MH 175 watt
ballast. these will run them no problem. as It used be labeled as such probe MH or MV before Mercury ballast
bans

Or maybe just go big with this and a 1000 watt bulb.



Howard Lighting M-1000-4T-CWA-K 1000W Quad Tap Metal Halide Ballast Kit https://www.amazon.com/dp/B00435KYHC/ref=cm_sw_r_other_apa_i_ez4wCb04A5F2Z

How do I deactivate the ignitor? Cut a wire?
Thanks

Is the ignitor the metal thing I thought was a capacitor? Just unhook it?

Okay, so first, if the lamp is 150w or under (which I'm guessing it is since that ballast looks like a lower wattage GE OEM) it will work but the lamp will cycle on and off. You can also disable the ignitor by disconnecting the white wire and capping it off. I don't know anything about using mercury vapors for fishing, but 1000w might be a little overkill.

Funkybulb
Thanks for your assistance in this. As it is it will cycle now and I don't want that. If I cap off the white wire from the white plastic thing will that keep it on and not cycle?

Cap at transformer? Or just pick a number from the Pic attached...

MV's are 100V arc lamps, so need an open circuit voltage (aka OCV, voltage without any load) at the ballast output
If it is HPS under 150W or the S55, it won't run the MV even without the ignitor. These ballasts are for a 55V arc lamp, so use OCV of just 120V (the mains; not taking into account the ignitor spikes). So these will never run any MV in any way. They may ignite it, but then it will cycle (the 100V arc voltage of an MV is just too much to maintain the arc with just 120V OCV).

The S56 and higher wattages are of higher arc voltage, so higher OCV.
The only HPS somehow compatible with MV is the S56 150W HPS ballast (with a 175W MV lamp), you just need to disconnect the Neutral wire from the ignitor (ignitor is a small thing with 3 wires, one connected to the lamp, one to Neutral, one to the tap in the ballast secondary), so it won't generate the HV pulses.
The pulse start MH are all wattages in the 50..250W range of about 100V arc lamps, so voltage wise compatible with MV.
You just have to find one with suitable arc current. There the only compatible are the 70WMH to 100WMV, 100WMH to 125WMV and 150WMH to 175WMV. And again, you  have to deactivate the ignitor (disconnect its Neutral wire).

So then these are all out of the picture then with max at 150 I gather?

When I worked for the city in their street lighting department I would occasionally sneak mercury vapor bulbs into the HPS fixtures. If it’s a 200 watt or greater HPS fixture, it will strike and maintain an arc in a mercury bulb. I would typically put 175W mercury bulbs in 200W HPS fixtures, 250W in 250W, and 400W in 400W fixtures. These lights are still running fine several years later and look great. The smaller wattage ballast for HPS don’t have enough voltage to sustain the arc on lower wattage mercury bulbs and will cycle.