The H380 Spectral Halo II is a high-output LED grow light from Kessil designed for serious plant / macroalgae cultivation (including use in refugia), especially where you need deep penetration, strong output, and spectral flexibility. It builds on earlier models (like the H350), delivering greater power and enhanced spectrum control. Its features make it suited both for vegetative-growth phases and for flowering or bloom phases.

How It Works the LED Grow Light H380 Spectral Halo II by  Kessil 

• Switchable Spectrum
  The H380 offers two full-spectrum modes: Extreme Purple for vegetative growth (encouraging leafy, lush, dense growth), and Extreme Magenta for bloom / flowering phases (to promote yield, flowers, fruit, or reproductive growth). It also includes UV LED chips to supplement spectrum for wavelengths that are often beneficial but under-used.

• Dense Matrix LED Technology
  The light source clusters many LED chips into a densely packed array (cluster), with optics (reflectors, lenses) that ensure the light emitted is well mixed (to avoid hot-spots) and highly focused / directed to maximize penetration into plant mass or algae mats. This design helps deliver effective light intensity even deep into the canopy.

• Enhanced Power & Penetration
  Compared to earlier Kessil grow models (notably the H350 line), the H380 is about 30% more powerful. That means better penetration (i.e. light reaching deeper into dense or taller plant growth), and a larger usable area under good conditions. The redesign includes a better internal reflector to focus more of the light downward into the plant canopy.

• Adjustable Intensity and Use Control
  You can dim / adjust intensity between 10-100%, depending on plant stage or distance from plants. Spectrum switching is done via a knob or dial on the light body. This lets you fine-tune depending on what your plants / algae need at different phases.

• Cooling and Thermal Management
  Though it’s fairly powerful, it has been designed to manage heat well so output remains more stable over time, and longevity is preserved. The materials / heatsinks / design reduce losses due to heat.

Specifications

Here are the technical details for the H380 Spectral Halo II:

• Power Consumption: ~ 90 watts maximum at full output.

• Power Supply/Input/Output: Accepts 100-240V AC input; DC output around 19V - with a current draw of ~ 4.74A.

• Dimensions: About 4.5″ × 4″ (length × diameter), or ≈ 114 mm × 101 mm.

• Weight: ≈ 520 g.

• Coverage: One unit can cover a surface diameter of about 24″ (≈ 60 cm) with penetration of about 3 feet (~ 90 cm) under good conditions. (Although average or effective penetration will be less, depending on distance, obstructions, foliage, etc.)

• Spectra Provided:
      • Extreme Purple (vegetative / growth) spectrum, plus
      • Extreme Magenta (bloom / flowering) spectrum, each including UV elements.

• Light Control: Spectrum switch knob; intensity dial (10-100%) on unit. No advanced onboard sensor; no full external smart controller built in (unless combined with other accessories) for more complex scheduling.

• What’s Included: Light unit; power supply; hanging / mounting accessories (hooks / suspension rings / extension where applicable).

Advantages when using LED Grow Light H380 Spectral Halo II 

• Very strong output with good spectral tailoring — allows you to tune your light for different growth phases.

• Excellent penetration: can reach well into plant mass / algae growth, which is particularly useful for thick or tall growth.

• Dense matrix / optics design gives even light mixing (less hot spots, more even coverage).

• Adjustable intensity / spectrum offers flexibility, so you don’t need separate fixtures for growth vs bloom.

• Relatively energy efficient for its output compared to older LEDs or HID systems.

Things to Watch Out For

• Even though powerful, mounting height matters: if too high, you lose intensity, especially at edges; if too low, you might risk bleaching sensitive plants or algae, or overheating.

• The coverage area is large, but real effective usable area (for e.g. maximum yield) may be smaller than claimed, depending on plant height, density, water clarity, etc.

• Control is basic: On/off + spectrum switch + dimmer. If you want advanced scheduling / remote control / extremely precise programming, you’ll need external controllers or smart accessories.

• Heat is better managed than older models, but still needs good ventilation / environment so the unit doesn’t overheat or degrade prematurely.

• Since the product is somewhat older, parts/accessories or replacements may be harder to find (depending on region), especially if discontinued or replaced by newer models.

Practical Tips 

• Position the light so the canopy is within its optimal penetration distance — you’ll get the best growth if you hang it at the right height (not too far, so light is strong; not too close so you don’t burn).

• Use the Extreme Purple spectrum during the vegetative / algae growth phase; switch to Extreme Magenta when you want to enhance flowering / reproductive growth.

• During transition phases, or when starting new organisms under this light, acclimate: begin at lower intensity and gradually increase to full output to avoid stress.

• Monitor your nutrient levels (nitrates, phosphates) — with strong lighting, algae / plants grow quickly and use nutrients faster; you may need to adjust feeding or flow accordingly.

• Clean the lens / reflector periodically; ensure water / salt remains from splashes don’t accumulate, as fouling will reduce effective light output.

• In a refugium setup, ensure enough flow so that macroalgae are well exposed to light and do not shade themselves or stack too much, which defeats penetration.

The Kessil H380 Spectral Halo II is a high-powered, relatively compact LED grow light offering two strong full-spectra with UV, good penetration, and flexibility. It works well in demanding growth situations (thick macroalgae, tall plants, transitions between growth and bloom phases). If your setup requires strong light (good depth, density) and you want spectrum control without going to large multi-fixture arrays, the H380 is a solid option.