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How much are your old lights costing you?

Let’s be real, grow lights and reflectors wear out over time. And if you’re not on top of it, your yields can take a serious hit. So, how much yield are you losing?

Check out our latest blog to get the scoop on why lamps degrade, how reflectors lose their shine, and what you can do to keep your plants thriving. Trust me, you don’t wanna miss this!

Alright, let’s talk about grow lights. Just like anything else, they don’t last forever. Over time, both your lights and reflectors lose their edge, and that can seriously mess with your yields. Here’s the lowdown on why this happens and what you can do about it.

Why Do Lamps Degrade?

Your HPS and CMH lamps aren’t immune to wear and tear. Here’s why their light output drops:

Physical changes: Electrodes inside the lamp wear out.

Chemical shifts: Metals in the arc tube change over time.

Why Do Reflectors Lose Reflectivity?

Heat is the main problem here. It causes oxidation on reflector surfaces. Even high-quality reflectors lose about 1% reflectivity every 1000 hours. Plus, dust, dirt, and spray residues don’t help either.

How Does Light Loss Affect Your Yields?

It’s simple: less light means less yield. If your lamp and reflector lose 5% of their light output, expect a 5% drop in yield. With most reflectors, 50% of the light hits them, so a 5% drop in reflectivity means you’re looking at a 0.5% yield loss.

How Bright Is Your Bulb?

Different lamps degrade at different rates. For a typical growing year (6570 hours for Veg), (4680 hours for Flower) here’s what you need to know:

HPS lamps: More durable than CMH lamps.

Standard cycle Veg: 18 hours/day for 365 days = 6570 hours.

Standar cycle for Flower 12 hours/day for 365  = 4680 hours.

Should You Change Your Reflector Regularly?

We set out to find out if there really is a difference between a brand-new reflector and one that has had a year's use. For many years, the trusty High Pressure Sodium (HPS) grow light has dominated the market. Even though LED grow lights have made significant advances, HPS lights are still widely used because of their reliability and cost-effectiveness.

While LEDs are plug-and-play and last for years with minimal maintenance, HPS and other HID lights need regular attention. It's well-known that HPS lamps lose efficiency over time and should be replaced regularly. We recommend changing reflectors about once a year as well, because the heat and intense light degrade the reflective surface. 

Testing Reflector Efficiency

We conducted a test using our  popular 1000w double ended fixture, comparing a new reflector to one that had been used for a full year. Here’s what we found:

New Reflector: PPFD measured at 775 μmol/m²/sec.

1-Year-Old Reflector: PPFD measured at 730 μmol/m²/sec.

This is a loss of 45 μmol/m²/sec, or almost 6%! Since light intensity is directly related to crop yield, a 6% reduction in light results in a 6% decrease in yield. That's significant!

Cost of Yield Loss

Let’s put this in perspective. If your crop sells for $1200 per pound, and your yield drops by 6%, you’re losing $72 per pound. Over multiple pounds, that loss adds up quickly. Can you afford to lose 6% of your yield when replacing your reflector costs much less than the lost yield value? If you grow high-value crops, the cost of a new reflector can be recouped in the first grow cycle. After that, it's all profit!

When Should You Replace Your Lamps?

Don’t push your luck with old lamps. Here’s when to swap them out:

HPS: Every 4000-5000 hours.

CMH: Every 2000-3000 hours.

How Often Should You Replace Reflectors?

At least every 12 months. Remember, half of your light hits the reflector, so even a 1% drop costs you 0.5% of your yield.

Keep growing fire. Keep your grow room lit and productive by staying on top of your lighting maintenance. For all your lighting needs, visit us at

Author: Gustavo Razo


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