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QUICK VERDICT
Our picks at a glance
For 40–50cm cubes, start with the AI Prime 16HD and Red Sea ReefLED G2 60. Wider 60cm nanos need a more careful choice about coverage and how the light is mounted.
Best value for small cubes
AI Prime 16HD
See prices below
40–45cm cube
Search Amazon UK ↗Best for a 45–50cm cube
ReefLED G2 60
See prices below
Up to 50 × 50cm
Search Amazon UK ↗Best for 60cm-wide nanos
Reef Flare Pro S
See prices below
60cm wide × about 45–50cm deep
Search Amazon UK ↗OUR PICKS IN DETAIL
Who each one is really for
Best value for small cubes
AI Prime 16HD
Best for
40–45cm cube
Why we picked it
Good-value compact light with app control; easy to find in the UK
The catch
Published coverage doesn’t guarantee enough light at every edge and depth.
Yes, for a compact cube, once you’ve checked where your corals will sit and the price including a mount.
Search Amazon UK ↗Best for a 45–50cm cube
ReefLED G2 60
Best for
Up to 50 × 50cm
Why we picked it
Red Sea publishes a 50 × 50 × 50cm test geometry
The catch
Red Sea’s app and mounting options need to suit the rest of your setup.
Yes, if your tank matches Red Sea’s published test size and you’ll use the ReefBeat app.
Search Amazon UK ↗Best for 60cm-wide nanos
Reef Flare Pro S
Best for
60cm wide × about 45–50cm deep
Why we picked it
Maker claims up to 60 × 60cm coverage
The catch
The coverage figure is the maker’s claim, not our own PAR measurement.
Yes, for a 60cm-wide tank. Leave some margin if demanding corals will sit near the edges.
Search Amazon UK ↗HOW WE RESEARCHED
How we chose
We compared manuals, manufacturer specifications, current UK retailer listings, running requirements, ownership costs and support. This is desk research, not hands-on testing, and where something is uncertain we say so.
- Tank length and depth
- Published coverage
- Mounting cost and clearance
- App and control
- Where your corals will sit
The best light for each tank size
| Tank size / examples | Start with | Also consider |
|---|---|---|
| 40–45cm cube Aqua One MiniReef 90; Red Sea MAX NANO Cube footprint | AI Prime 16HD Good-value compact light with app control; easy to find in the UK | ReefLED G2 60 A good alternative if Red Sea’s ReefBeat app suits your setup |
| Up to 50 × 50cm Larger cubes, or a single central rock island | ReefLED G2 60 Red Sea publishes a 50 × 50 × 50cm test geometry | AI Prime 16HD UK sellers often quote 50 × 50cm; allow some margin if demanding corals sit near the edges |
| 60cm wide × about 45–50cm deep Aqua One MiniReef 120; MAX NANO XL-class footprint | Reef Flare Pro S Maker claims up to 60 × 60cm coverage | Kessil A360XE Claimed 61 × 61cm for a mixed reef; controller and mount may cost extra |
| 60cm wide, premium control Corals spread around the tank, or unsure what you’ll keep later | Radion XR15 G6 Pro 61 × 61cm recommended spread with broad programming | Two smaller sources Costs more, but can cast fewer shadows than one central light |
Four things people forget to check
Make sure the arm’s clamp clears the trim, lid and filtration chamber. A “compatible” light can still come with a mount that doesn’t fit.
Small tanks often sit on desks or low cabinets, so mounting height, shades and where you sit really matter.
One light is simpler. Two can soften shadows and let you control the overlap, but double the mounts, cables and settings.
If you have a Fluval Evo or a complete Red Sea MAX, work out what the included light can’t do before you replace it.
What we’d look at first
For a new 45cm cube, start by comparing the AI Prime 16HD and the ReefLED G2 60. For a 60cm-wide nano that came without a light, compare the Reef Flare Pro S, Kessil A360XE and Radion XR15 G6 Pro, each priced with its mount. This is a shortlist, not a ranking: where your corals sit and which app you prefer will decide the winner.
Check the running cost too
At our standard UK planning rate, a 60W light running at full power for 10 hours a day costs about £57 a year; an 80W light about £76. Real schedules usually use less. Work out your own figure with the electricity calculator.
WHICH ONE FITS YOU?
Match the light to the area you need to light
A 40–45cm cube
One compact light is a sensible start, because a central light can cover a single coral island. Leave some margin at the edges, and allow for your real mounting height before trusting the quoted footprint.
A 50cm cube with demanding corals
Published coverage can point you to likely lights, but coral height and shadows can matter more than the glass size. A single central light won’t give even intensity behind rockwork.
A 60cm-wide nano
One bigger light is clean and simple; two smaller lights can give better overlap and fewer shadows. Compare the full mounted price, combined power, control and how cluttered it looks, not just the light’s price.
HOW TO CHOOSE
What to check before you buy
Map out your coral zone
Mark the length, width and depth where light-hungry corals will actually live. Bare sand and back corners don’t need the same intensity as the top of your rockwork.
Allow for mounting height
Coverage claims depend on how high the light sits, and spread usually comes at the cost of intensity. Check the recommended mount, the tank rim and the space above as one.
Claims aren’t evidence
Watts and quoted footprints don’t prove the PAR at each spot. Use them to build a shortlist, then confirm with measurements or a cautious placement plan.
Think about heat and control
App quality, schedules, acclimation modes, fan noise and how it recovers after a power cut all affect daily life with a light. It’s more than its LED count and peak watts.
RUNNING COSTS
What it costs after you buy it
Mounts
Tank arms, hanging kits, rails, diffusers and shades can add a lot. Compare full installations, not a bare light against a rival that includes its mount.
Electricity and heat
A light rarely runs every channel at full power, but wattage still affects your bill and room temperature. Work it out from your real schedule rather than assuming it costs nothing.
Room to grow
Upgrading your corals or widening your aquascape may mean a second light later. The cheapest light now can cost more if it leaves you with an awkward upgrade.
ALTERNATIVES
Other options worth a look
Keep the light you have
If your current light suits your corals and where they sit, tweaking the schedule and aquascape may achieve more than replacing it straight away.
Use two lights
Two smaller lights can improve overlap on a 60cm tank, but mean more mounts, more cables, more setup and a higher total price.
HOW WE RANK
What it takes to make our list
It has to fit
Before we compare features, we rule out anything that doesn’t suit the tank, the installation or the job. A famous name can’t win if its size, operating range, connections or controls make it a poor match.
Claims need context
A spec sheet tells you what a product is designed to do, not how it will behave in your reef. So we look at the conditions behind every capacity, flow, output and accuracy claim, and flag any conclusion that’s an informed judgement rather than a measurement.
Every pick shows its catch
Each product’s main drawback sits right next to its biggest strength. We don’t hide a support worry, a missing accessory, a vague rating or a pricey ecosystem just because the product is the best choice for one type of buyer.
UK ownership breaks ties
Availability, what’s actually in the box, consumables, spares, UK plugs and the warranty route all count. When two products do the job equally well, the one that’s easier to own in the UK gets the stronger recommendation.
We don’t publish a one-size-fits-all league table. Each award answers a different buying situation, and the final verdict explains which trade-off we’d make. If your tank, budget or routine doesn’t match any of them, use the checks above to build your own shortlist rather than just buying the top badge.
COMMON QUESTIONS
Frequently asked questions
Can I choose a reef light based on tank litres?
No. Lighting depends mainly on the tank’s shape and what you keep. Two tanks with the same litres can have very different surface areas and depths.
Is a light with bigger coverage claims better?
Not necessarily. Wider spread can mean lower intensity, and the claim may be based on a different mounting height or coral layout from yours.
Do I need a PAR meter?
It’s the clearest way to see what light your corals actually get. Without one, a cautious schedule, published coverage data and careful coral placement still help you choose well.
BEFORE YOU ORDER
Three checks before you pay
Confirm the exact model
Shop listings often mix up generations, sizes and regional versions. Check the full model code, UK plug, included accessories and who handles the warranty against the manufacturer’s own details. Save the product page and spec sheet in case the listing changes.
Price everything it needs
Add the mount, controller, adapters, consumables, test kit and likely replacement parts you’ll need to run it. Compare that first-year total, not the headline price, and keep a little extra for plumbing, cable tidying or the fitting you forgot.
Measure twice at home
Measure your tank, cabinet, sump chamber, glass, sockets and the space you need to service it. Then write down the one job this kit has to do, and how you’ll know it’s working. If it won’t fit, or you can’t tell whether it’s doing its job, it’s the wrong choice.
Prices and stock change quickly. Every price here is a dated UK snapshot, so confirm the total at checkout and the returns terms, and don’t swap in a similarly named model without running these checks again.
OUR VERDICT
Buy for where your corals live, not the tank’s label
Start with the AI Prime or ReefLED for compact cubes, and compare wider or multi-light setups for 60cm tanks. Whatever we recommend, your actual mounting, aquascape and coral zone have the final say.
After installing, log any light changes in the free Reef Companion next to your test results, so you can see how your corals respond over time.