Hydroponics, the science of growing plants in a mineral nutrient solution (i.e. souped-up water that can require chemistry credentials), gets a lot of attention in growing circles, but we vastly prefer to sow our homegrown health revolution the natural way.
Conversion Bulbs are unique in that they allow you to use your High Pressure Sodium bulbs with a Metal Halide ballast, or vice versa; you can use a Metal Halide bulb with a High Pressure Sodium ballast. This is helpful if you already own an HPS or MH ballast but have the need or desire to use an opposite bulb; getting a conversion bulb is the least expensive route to accomplish this.
Keep in mind that the main difference between MH ballasts and HPS ballasts is the fact that HPS ballasts have an igniter while MH ballasts do not. All electronic ballasts will illuminate MH bulbs, however, only HPS specific ballasts or switchable ballasts will illuminate HPS bulbs - unless you get a conversion bulb.
We know - this can be confusing, so please feel free to contact us with ANY questions or comments here.