For a typical 90-gallon reef measuring about 48 × 18 inches, two AquaIllumination Hydra 32 HD fixtures are a defensible starting point for soft corals, LPS, or a mixed reef. An SPS-dominant aquarium needs tighter spacing and verification with PAR measurements; BRS guidance is one Hydra 32 per 12–15 inches of tank length for SPS. Your actual footprint, mounting height, rockwork, coral positions, and desired intensity determine the final setup.
Start with the tank footprint, not the gallon label
“90 gallons” does not describe how evenly a light will cover the aquarium. Bulk Reef Supply (BRS) uses 48 inches long by 18 inches front-to-back as a typical 90-gallon footprint. Measure your tank, including its actual water depth and any bracing, before choosing a fixture count.
Coverage is especially important at the front and back glass and around rockwork. A light that produces adequate intensity directly beneath its lens can still leave dim zones, hot spots, or coral shadows elsewhere.
Best starting configuration by coral type
| Reef goal | Starting guidance for a 48-inch tank | What to verify |
|---|---|---|
| Soft corals, LPS, or mixed reef | Two Hydra 32 HD fixtures; BRS guidance is one fixture per 24 inches of tank length. | PAR at coral locations, edge coverage, hot spots, and shadowing after rockwork is installed. |
| SPS-dominant reef | Tighter placement: BRS recommends one Hydra 32 per 12–15 inches of tank length. A 48-inch tank therefore points to roughly three to four fixtures as an initial spacing concept, not a guaranteed prescription. | PAR distribution through the full coral-growing area and whether colonies shade one another as they grow. |
Fixture count is only a starting point. Mounting height, lens spread, intensity, aquascape height, and coral placement can change the result substantially.
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- VIPARSPECTRA timer control series V165 LED aquarium light is scientifically engineered to keep the balance of the PAR output and perfect for 24"x24" coverage
- Dimmer & Timer Functions: Dimmable feature adjusts the brightness of two channels individually from 0%-100%; internal timer allows you to turn the V165 reef light on and off automatically
- Enhanced Growth Full Spectrum: With our proprietary layout, which is contributed by thousands of ReefCentral members, V165 led lamps have had years of success
- Suitable for All Photosynthetic Corals: Be sure to acclimate your tank or new corals to the new light by increasing the aquarium lights exposure/intensity gradually
- Two Ways to Setup: You can operate the coral light with control knob or remote - one remote in hand, everything is simple
Fixture options worth comparing
AquaIllumination Hydra 32 HD
The Hydra 32 HD is the clearest named recommendation for this tank size because BRS gives spacing guidance specifically for the model. Two units suit a typical 48-inch mixed reef as a starting configuration; SPS systems need the tighter spacing described above. BRS also reported that four Hydra 32 HD units delivered up to 15% better performance and coverage than three Hydra 64HD fixtures over its 48-inch test aquarium. That is a result from BRS’s test, not a universal ranking of every installation.
Red Sea ReefLED 90
Red Sea documentation lists 60 × 60 cm (24 × 24 inches) of coverage for a ReefLED 90. BRS tested two ReefLED 90 fixtures over a 48 × 24-inch, 120-gallon aquarium at an 8.5-inch mounting height. The test averaged 185 PAR at 12 inches depth and 168 PAR at 18 inches depth. Three fixtures reached the SPS target range cited by BRS across that tested tank through 18 inches of depth.
Rank #2
- Focus most power at 440-480nm wavelengths to enhance coral fluorescence and boost growth with minimal energy waste
- Custom 90° beam-angle lens optics deliver concentrated PAR output while ensuring optimal coverage in deeper aquariums
- Featuring a removable dust-resistant mesh, the cooling system operates near-silently while maintaining exceptional heat dissipation efficiency
- Effortlessly control the NavaReef through the built-in timer setting or external controller connectivity
- Compatible with standard Tank Mount (included) supporting rimmed/rimless tank and optional Hanging Kit (sold separately) for open-top installations
Those measurements are not a promise for a 90-gallon aquarium: the tested tank was 24 inches front-to-back rather than the typical 18-inch footprint, and PAR changes with mounting height, water depth, rockwork, and output settings.
EcoTech Marine Radion XR15/XR30
Radion fixtures are a premium alternative family with official installation guidance. The available EcoTech coverage document is an older, general guide; it does not establish a current G6-specific fixture count or a test result for a 90-gallon aquarium. Treat any Radion layout as a configuration to validate with PAR rather than as a tank-size guarantee.
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- The proven and enhanced violet and blue spectrum offers ideal wavelengths and intensity for better coral growth and fluorescence
- A custom designed wide-angle optical system achieves extensive coverage, gets even PAR distribution, and eliminates hotspots
- Advanced heat management features a new fan and a redesigned heatsink that ensures superior heat dispersion with minimal noise
- With 2 USB-C control ports, the HyperReef can be easily connected to an external controller (sold separately) for endless customization
- Various mounting options for the HyperReef Gen 2 are available, featuring multiple light mounting systems, single light mounting arms, and hanging kits
How to choose between them
- Match coverage to the footprint: compare the illuminated area at your planned mounting height, not the manufacturer’s aquarium-gallon label alone.
- Match intensity to the coral plan: SPS generally demands denser, more even coverage than soft corals or many LPS arrangements.
- Check distribution: look for edge drop-off, central hot spots, and shadows behind colonies and rock structures.
- Confirm mounting hardware: verify that the arm, bracket, or hanging kit fits your tank and the exact fixture model. A Hydra HMS mount is a relevant hardware category, but compatibility and stock should be confirmed before purchase.
- Consider the control ecosystem: app features, scheduling, acclimation controls, noise, power use, and integration with equipment you already own can outweigh small differences in peak output.
- Use evidence carefully: a measured PAR result is useful only when the tank dimensions, depth, mounting height, fixture count, and settings are comparable to yours.
Measure and tune the installed lights
Published coverage charts cannot account for your aquascape. BRS advises setting the fixtures in place, measuring PAR in the actual aquarium, and adjusting position or output to reach the needs of the corals at their real locations. An LED-capable PAR meter is optional but useful for this job.
- Install the fixtures at the intended height and center them over the usable coral-growing area.
- Record readings near the surface, mid-water, sand bed, front and back zones, and beneath likely shadow areas.
- Compare readings at coral positions rather than judging brightness from the viewing angle.
- Adjust fixture spacing, mounting height, or output to reduce severe hot spots and dark edges.
- Increase intensity gradually when acclimating newly installed lights, especially if the previous system was weaker.
- Recheck after adding rock or when fast-growing colonies begin shading lower branches.
Keep a simple record of mounting height, intensity, schedule, and measurement locations. If a coral responds poorly, change one variable at a time so you can identify whether light distribution, intensity, flow, or another husbandry factor is responsible.
Rank #4
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- REMOTE & TOUCH CONTROL & JOINT CONTROL - G5 95W saltwater aquarium lighting support remote and touch control special design for marine saltwater tanks. Built-in Sunrise Sunset Moonlight program and DIY modes make G5 reef lighting could imitate nature lighting of sea perfectly. Master slave Group control make sure master G5 could synchronize the data of all lights, easier operation
- BETTER HEAT DISSIPATION & NO NOISE -Smart two-rollers silent temperature control fans ensuring optimal LEDs' working conditions. Noise standards is lower than 44.7 db(A), fast heat transfer and create you a comfortable environment. G5 is very good coral lights for saltwater tanks
- FLEXIBLE ALUMINUM AQUARIUM STAND - Special Anti-rust design flexible full aluminum with oxidation bracket suitable for different size of coral tanks. Oblate base efficiently increase stressed area and protect coral reef tank well. Ideal coverage of G5 coral light is 20-28 inch. Tank glass thickness: 0.2-1.5 inch
- NOTICE - A remote included in G5 reef tank light, install battery before use! Rimmed tank plastic should less than 1.5", please cut it little if larger 1.5". Smatfarm G5 aquarium light provide One year without worries. Full-time customer service, Emails and messages will be replied within 24 hours! Please contact us first if any problem with G5 coral lighting!
Common buying mistakes
Buying for gallons alone
A fixture advertised for a certain aquarium volume may not cover a long, shallow tank evenly. Length and front-to-back coverage are more actionable than the volume label.
Using a single strong fixture over a long tank
One intense light can create a bright center and dim ends. Multiple fixtures usually provide more placement flexibility and reduce the chance that one lens or emitter becomes a single point of failure.
Best Value
- [140watt Powerful Output & Six Channels]-G6 Aquarium Sun has powerful 140w maximum output and six channels (White / blue / violet / ultraviole / green / red) with dimmable and timer lighting system. G6 Reef tank light owns 52pcs 5Watt high power LEDs, G6 saltwater aquarium light can meet oversized saltwater tanks with high penetration and wide coverage.Please use on tanks of 20 gallons or more
- [Intelligent Reef Tank Control System]-G6 coral light support 2.4G wirelesss master slave group control.Touch & Remote & Group Control make easy setting coral lights for saltwater tanks. Bulit-in SPS LPS MIX program modes,dimming six channels at 1% interval,set sunrise sunset moonlight time.G6 can perfectly simulate natural lighting for corals and fish tanks
- [Super Silent & Good Heat Dissipation]-G6 reef lights adopt super silent smart fan and full-coverage aluminum heatsink.Enlarge heat dissipation area by 300%.For different aquarium tanks G6 reef lighting can provide enough beam quietly.Strong penetration and wide coverage.The noise less than 40dB.Quietly enjoy corals and fish tank in comfortable environment
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Copying a PAR number without its conditions
The ReefLED measurements above came from a 48 × 24-inch tank, at stated depths and an 8.5-inch mounting height. Transplanting those numbers to a different footprint or height is not a valid comparison.
Ignoring future coral growth
Initial readings can look acceptable while mature colonies shade neighboring corals. Plan for the structure and density your reef is intended to reach, not only for newly mounted frags.
Practical recommendation
For a standard 48 × 18-inch 90-gallon mixed reef, begin by evaluating two Hydra 32 HD fixtures, then measure PAR and correct coverage after the aquascape is complete. Choose tighter Hydra spacing for an SPS-focused plan. Consider ReefLED 90 or Radion fixtures when their control system, mounting options, or ecosystem better fit your equipment, but do not transfer the cited ReefLED test or the older Radion guide into a guaranteed 90-gallon specification.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
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