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Grower's Choice 315W CMH Grow Light - Growers Choice - Happy Hydro Grower's Choice 315W CMH Grow Light - Growers Choice - Happy Hydro Grower's Choice 315W CMH Grow Light - Growers Choice - Happy Hydro Grower's Choice 315W CMH Grow Light - Growers Choice - Happy Hydro Grower's Choice 315W CMH Grow Light - Growers Choice - Happy Hydro

Grower's Choice 315W CMH Grow Light

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Growers Choice
Price:
$179.00 $249.00
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Description

Grower's Choice 315W CMH Grow Light | Happy Hydro

Full-spectrum light that actually matches sunlight, at 315 watts

The Grower's Choice GC-315 is a complete ceramic metal halide fixture with a built-in digital ballast, open reflector, and your choice of lamp spectrum. CMH produces a broader, more balanced spectrum than HPS with a CRI up to 97, which means your plants see light closer to what they'd get outdoors. The fixture runs 120V/240V, dims without external controllers, and includes full circuit protection so you're not replacing ballasts after a power surge.

3-year warranty 120V/240V compatible Controller compatible
Free shipping on orders over $49
30-day returns on all orders
Serving growers since 2006
Side by side
315W CMH vs. a standard 600W HPS
600W HPS
  • Narrow spectrum, heavy in yellow/orange, almost no UV or blue
  • 600W draw plus additional cooling costs
  • Separate ballast, reflector, socket, and lamp to assemble
  • Magnetic ballasts hum, flicker, and lose efficiency over time
  • Bulbs degrade quickly, typically need replacement every 6 to 9 months
  • No built-in dimming or fault protection
GC-315 CMH
  • Full spectrum with UV, blue, red, and far-red, CRI up to 97
  • 315W draw, nearly half the power for competitive PAR output
  • All-in-one fixture: ballast, reflector, and lamp in one unit
  • Digital square-wave ballast, no hum, no flicker, consistent output
  • 15,000-hour rated lamp life, roughly double a standard HPS bulb
  • Built-in dimming dial and full circuit protection against surges
What makes it different
Built for real grow rooms, not spec sheets

Closest spectrum to sunlight available in HID CRI up to 97

The 4K lamp scores a 97 CRI, meaning its spectral output is nearly identical to natural daylight. The 3K lamp sits at CRI 90 with enhanced red for flowering. Plants respond to this broader spectrum with tighter internodal spacing and more uniform growth.

Low-frequency square wave ballast

The digital ballast drives the lamp with a low-frequency square wave, which is up to 30% more efficient than magnetic ballasts and maintains that efficiency for the life of the unit. No internal fans needed because the case design acts as a passive heat sink.

Full circuit protection with 3-second self-test

On every ignition, the ballast runs a 3-second diagnostic. It protects against open circuit, short circuit, over-voltage, under-voltage, and over-temperature faults. If something is wrong, the ballast enters protection mode instead of damaging itself or the lamp.

Dimmable with Smart Step and Super Lumen modes

Turn the dial to reduce output when plants are young or temperatures are high. Super Lumen pushes the lamp past rated wattage for maximum PAR when you need peak intensity during late flower.

Runs cooler than HPS at comparable PAR

At 315W, this fixture produces significantly less radiant heat than a 600W HPS. In small tents or rooms without dedicated HVAC, that can be the difference between manageable temperatures and constant heat stress.

Compatible with Grower's Choice Master Controller

Daisy-chain up to 100 fixtures per zone using the optional Master Lighting Controller. Supports timed on/off, sunrise/sunset ramping, and dual thermal probe auto-dim shutdown for commercial setups.

Specs
Technical specifications
Wattage
315W
Input voltage
120V / 240V (50/60 Hz)
PAR output (3K lamp)
570 µmol/s initial
Coverage area
3' x 3' flower, 3.5' x 3.5' veg
Lamp life
15,000 hours rated
Input current
2.9A @ 120V, 1.5A @ 240V
Power factor
> 0.98
Warranty
3 years (Grower's Choice)

Setting up your GC-315

1

Hang the fixture

Use the included hanging hardware to mount the fixture from your tent crossbars or ceiling hooks. Adjust height to 18 to 24 inches above the canopy for flowering, 24 to 30 inches for veg.

2

Install the lamp

Insert the 315W CMH lamp into the built-in socket. The lamp seats horizontally in the open reflector. Handle by the base only, not the glass envelope.

3

Set the power level

Turn the ballast dial to your preferred output. Start lower for seedlings or clones, then step up to full power as plants mature. Use Super Lumen mode during peak flower if temperatures allow.

4

Plug in and grow

Connect to any standard 120V outlet (ships with a 120V plug). For 240V operation, swap the cord end or hardwire. The ballast auto-detects frequency and adjusts output to prevent flicker.

In the box
Everything you need to start growing
Included with every fixture
  • GC-315W all-in-one fixture with integrated digital ballast
  • One 315W CMH lamp (your choice of spectrum)
  • Open reflector with horizontal lamp mount
  • 120V power cord (pre-attached)
  • Hanging hardware
  • 3-year manufacturer warranty
Lamp options
  • 3K-R (3,100K): Full spectrum optimized for bloom, enhanced red, CRI 90, 570 µmol/s
  • 4K (4,200K): Veg-optimized with heavy blue output, CRI 97, promotes tight internodal spacing
  • 10K MH Finishing: Metal halide finishing lamp for the final 2 weeks, boosts resin and aroma
  • No Bulb: Fixture only, bring your own 315W SE CMH lamp
Not sure which lamp to pick? The 3K-R is the most popular choice for growers who want one lamp for the full cycle. If you run separate veg and flower spaces, pair the 4K for veg with the 3K-R for flower. Call or email us: 716-217-0353 / help@happyhydro.com
Questions
Frequently asked questions
The GC-315 flowers a 3x3 area effectively and vegs a 3.5x3.5 area. In a 4x4 tent, you'll get solid growth in the center but the corners will be noticeably dimmer. For full 4x4 coverage in flower, most growers either run two 315W fixtures or step up to a 630W CMH or LED. If you're growing one or two large plants in the center of a 4x4, a single 315W can work fine.
LEDs in this price range typically pull similar wattage but produce a narrower, diode-driven spectrum. CMH's advantage is spectral quality: the broad, continuous spectrum is closer to sunlight than the peaked spectrum of most LEDs. Many growers report visibly healthier plants and tighter structure under CMH compared to budget LEDs. The trade-off is that CMH generates more heat and the lamp needs replacement every 15,000 hours. If heat is your main concern, LED may be the better fit. If spectrum quality matters more, CMH wins at this price.
Grower's Choice rates their CMH lamps at 15,000 hours. Running 18 hours per day in veg, that is roughly 2.3 years. Running 12 hours per day in flower, that is about 3.4 years. Spectrum and output do degrade over time, so many growers swap lamps every 12 to 18 months for peak performance. Replacement lamps are available separately on our site.
The ballast accepts both 120V and 240V input. It ships with a 120V plug. To run on 240V, you'll need to swap the plug or hardwire to a 240V circuit. Running on 240V draws less current (1.5A vs 2.9A), which is better if you're running multiple fixtures on the same breaker. The fixture auto-adjusts, no switch or setting needed.
Yes, any standard single-ended 315W CMH lamp with a PGZ18 base will fit. Grower's Choice lamps are optimized for this ballast's frequency and output, so using their lamps ensures the best spectral performance and longest lamp life. Third-party lamps will work but may not perform identically.
Not for a single fixture. A standard appliance timer handles on/off scheduling, and the built-in dial controls dimming. The optional Grower's Choice Master Lighting Controller becomes useful when you're running multiple fixtures and want centralized sunrise/sunset ramping, thermal monitoring, and auto-dim shutdown. We carry the controller separately if you need it later.
If you receive a defective or damaged unit, email us a photo at help@happyhydro.com and we'll make it right immediately: replacement or refund, your call. For change-of-mind returns, we accept returns within 30 days for items in new, resalable condition. If you're not sure whether this product is right for your setup, call us first at 716-217-0353. We'd rather answer your questions before you order.
Happy Hydro has been selling growing equipment since 2006. We've carried Grower's Choice for years because the systems work great and customers who buy them leave happy. Have questions before you order? Call 716-217-0353 or email help@happyhydro.com. We're easy to reach and happy to help!

Your Happy Hydro Shipping Experience

We ship fast from Buffalo, NY. Most orders land at your door in 3-5 business days. Free standard shipping on orders $49+, plain-box packaging, and real humans ready to help if anything goes sideways.

Free shipping on orders over $49
Plain-box discreet packaging
Serving growers since 2006
What to expect
When you order from Happy Hydro

Fast & Free on Orders $49+

Free standard shipping to the lower 48. Most orders ship same or next business day from our Buffalo, NY warehouse via UPS Ground or USPS Ground Advantage. Expedited options available at checkout.
* Soils may incur added fees for Western US delivery
* Some products ship direct from the vendor's warehouse to keep prices lower and get your order there faster

World-Class Customer Care

Our grower support team is here 10 am-4 pm EST, Monday-Friday. Call 716-217-0353 or email help@happyhydro.com.

Discreet & Secure Packaging

Every order ships in a plain brown box with no branding or logos. Your purchase stays 100% private. We can also ship to your local UPS Store on request.

Specs
Shipping details at a glance
Delivery time
3-5 business days
Default carrier
UPS Ground or USPS
Signature required
Orders over $500 only
Free shipping threshold
$49+ to the lower 48
International
Canada only Email help@happyhydro.com your address & a screenshot of your cart for a quote
Returns
30 days on most orders Exceptions apply — orders over $400, multi-box shipments, and some vendor items may incur return shipping charges. Full policy
Questions
Frequently asked questions
Shipping
Check the order confirmation sent to your email or phone after checkout — it includes a tracking link. If you use the Shop App, you can track your order there too.
Most orders arrive in 3-5 business days. Expedited options (2-day, overnight) are available at checkout if you need it sooner.
Signature is only required on orders over $500. For added privacy, we can ship to your local UPS Store so you pick it up on your own schedule — just ask.
We default to UPS Ground or USPS Ground Advantage. Select an expedited option at checkout and we'll use the appropriate carrier for that service.
  • P.O. boxes: Yes, for small and lightweight items.
  • International: Canada only. Email help@happyhydro.com your address and a screenshot of your cart for a shipping quote.
  • APO/FPO: Not currently available.
For Canadian orders, import duties and taxes are the buyer's responsibility. You'll complete payment using your tracking number at UPS.com when your package arrives.
Title and risk of loss pass to you once we hand off to the carrier, but that doesn't mean we leave you hanging. Email help@happyhydro.com and we'll work overtime to track it down and make it right.
Payment
We accept credit/debit cards, PayPal, Coinbase, and Happy Hydro gift cards. Your card is charged immediately at checkout.
Double-check your billing address and card number. For larger purchases, your bank may have flagged it — a quick call to authorize the transaction usually sorts it out.
Promotions
Enter your code in the "Promo code" box at checkout and click Apply. One code per order, but you can combine a gift card with a promo code if you have both.
Subscribe to our mailing list for exclusive discounts and early access to sales. You can sign up at the bottom of any page on our site.
Returns & Cancellations
Email help@happyhydro.com within 30 days of delivery and we'll get you a refund or replacement, your choice. Items must be in original packaging with all parts in resalable condition. Multi-light orders, grow tents, orders over $500, and multi-box shipments may incur return shipping charges. AK, HI, and international buyers are responsible for return and warranty shipping. Some vendor-specific policies may apply — check the product page for details.
Refunds are processed through Shopify within 10 business days. Most customers see the credit back in about 5 days.
Reply to your order confirmation email or email help@happyhydro.com as soon as possible. Canceled orders may incur a processing fee depending on your payment method:
  • Credit/debit card: 2.9%
  • PayPal or Venmo: 3.5%
  • International PayPal: 4.0%
  • American Express: 4.1%
  • Shop Pay Installments / PayTomorrow: 6.5%
Support & Policies
Call or chat with our grower support team at 716-217-0353, Monday-Friday 10 am-4 pm EST. You can also email help@happyhydro.com any time and we'll get back to you quickly.
Your privacy matters to us. Read our full policy at happyhydro.com/pages/privacy-policy.
Why Buy From Happy Hydro

Why Buy From Happy Hydro

Happy Hydro began as a pipe dream in a garage and has grown into something built almost entirely on word of mouth and repeat customers. Rather than focusing on raising margins and obsessing over profits, we've always believed that the right combination of competitive prices, superior products, and world-class customer service speaks for itself. Our philosophy will never change: when you're happy, we're happy.

Our commitment
What you can expect from Happy Hydro

Real People, Real Growers

Our grower support team isn't a call center. They know the products because they're passionate about growing. Reach us Monday-Friday, 10 am-4 pm EST at 716-217-0353 or help@happyhydro.com, before you order or after.

Hand-Picked by Growers, for Growers

Every brand we carry was chosen by our founders because it performs. We only stock premium brands we believe in, and every item is inspected before it leaves our warehouse.

Fair Prices and Free Shipping

We work hard to keep our prices as low as manufacturers allow, and we include free shipping on orders over $49 so there are no surprises at checkout. Find a lower price anywhere and we'll match it.

Authorized for Every Brand We Carry

We're an authorized dealer for every manufacturer on our site. That means you get the full manufacturer's warranty on every purchase. No grey market, no expired stock.

30-Day Returns on Most Orders

Hard to commit to a product you haven't tried. Return most items within 30 days in original condition and we'll take care of it. Read the full policy.

Secure Shopping, Private Data

Every transaction is SSL encrypted. We don't store payment information and we will never sell your data to anyone, ever.

Volume and Commercial Pricing

If you're a commercial grower or putting together a large order, reach out before you buy. We have pricing available that we can't advertise publicly. Call 716-217-0353 or email help@happyhydro.com and we'll take care of you.

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