Down in question they ask if this 400 watt hps is a conversion bulb and if it will work with MH ballast and they say yes, so would probably work with my ballast?
It's listed as an HPS lamp so won't likely work off a magnetic MH ballast like yours. You asked if it would work off a metal halide ballast but not a
magnetic core and coil metal halide ballast. I wouldn't buy it for your ballast.
VIVOSUN 2-Pack 400 Watt High Pressure Sodium HPS Grow Light Bulb Lamp - High PAR Enhanced Red and Orange Spectrums CCT 2100K, Ultra Bright 55,000 Lumens
Enhanced Red and Orange Spectrums are for flowering plants and the low CCT 2100K is also for flowering. MH is around 4200 - 10,000K. My 600W MH conversion bulb is 7200K. Those are the wrong bulbs for your ballast and would not work at all but would work as a flowering light in a digital ballast as they will do both automatically or in a magnetic HPS ballast.
One like this is what you want for flowering off your ballast I believe. Same as my 1000W one that runs off my 1000W MH ballast. This is not a conversion bulb but one with those enhanced reds and oranges needed for good flowering. Not cheap tho but damn good bulbs.
Hydroponic Supplies. Indoor Grow Supplies. Indoor Gardening. Canadian Owned.
happygrowsupplies.com
Ensure reliable and efficient startup of your HPS ballasts with the Keystone IGN-XG-02 250W-400W HPS Ignitor. This durable ignitor provides consistent performance and a 2-year warranty.
lightbulbsurplus.com
400watt ignitor for ballast??
I wouldn't be trying to incorporate that into your ballast unless you know what you are doing or can find very good instructions on U-Tube or somewhere. You could fry the ballast, bulb or yourself. Something like 450V coming off a magnetic core to the bulb. It is not plug and play.