What Causes A Bulb To Depreciate Anyway?
Start Up Firing: When your ballast strikes (fires) your MH or HPS bulb, it sends a massive voltage pulse to the bulb that is much higher than what the bulb runs at once it has been fired. This massive voltage ignition slightly harms the lamp. This is the primary source of blackening within the arc tube, which is actually microfractures caused by this intense voltage ignition. This process will slowly cause the properties of the arc tube to change, causing decreased intensity and color shift over time.
Temperature: Another factor that can decrease your lamps potential output is heat, or lackthereof. High Intensity Discharge (HPS and MH) bulbs create light photons via heat and pressure. Air cooling a lamp will cause a minimal decrease in bulb intensity. Refrigerated air such as that from an air conditioner or when it is very cold outside can cause a noticeable decrease in brightness. This decrease in brightness is caused because bulbs are designed to be ran at specific, hot temperatures that burn the beneficial salts and halides within them to produce the spectrum optimal for plants to photosynthesize.
Old Age & Power Draw: As a lamp ages, it may require a higher voltage to operate correctly. Digital ballasts can sense that a lamp is not coming up to full brightness and increase the power to a lamp. Unfortunately, magnetic ballasts do not. Instead, magnetic ballasts will keep the voltage to your lamp constant, and the intensity of your lamp will decrease. As lamps age on digital ballasts, the digital ballast will attempt to compensate by increasing the power to the bulb. So, digital ballasts will help keep your light output more consistent as they degrade, but possibly at the expense of more energy used. And this is no cure all for bulb degradation. If the aging lamp requires too much voltage, the ballast will shut down as a safety precaution. Your lamp may restart but it will continue to shut down because the voltage requirement is too high for the ballast.This is a typical sign that it is time to replace your lamp.
Regular Lamp Replacement is Essential
All that said, many of the beneficial salts (HPS) and halides (MH) within the lamp arc tube that are used to create the spectrum we're looking for is used up within 9 months of typical usage at 12 hours per day. As these magic chemicals are burned off, the spectrum of your lamp changes away from the photosynthetically optimal spectrum. The intensity of your lamp will also degrade over this same period by about 10%, depending on your lamp and possibly even more. These two factors combined can lead to more than +15% decreased yield after 9 months using the same bulb.
Growers House wants to make sure all of our customer's understand this information. With this information, our customers can make educated decisions on how to optimize their gardens and their budgets. Including our crazy low price on Eye Hortilux 1000W Super HPS Enhanced Lamps.
Happy Growing :)