Aquarium lighting guide

Not a quiz — just clear guidance. Use this page to choose the right lighting for your aquarium. Learn what matters (brightness, spectrum, size, mounting, water protection) and how to avoid common mistakes.

Practical guidelines No complicated formulas Focused on results

1. First: what do you want to light?

The right light depends mainly on your aquarium type and goals. Start here — so you don’t end up buying “by watts” or “by colour” only.

Fish-only / community tank
You mainly want a natural look, good visibility and a stable day/night rhythm. Light doesn’t need to be extremely strong.
Planted aquarium
Plants need more light and a usable spectrum. The more demanding the plants, the higher the light requirement. CO₂ and nutrients matter too.
Extra focus on colour rendering
Think vibrant fish colours and a nice presentation of wood/rocks. Choose stable output and a comfortable colour temperature.
Specific inhabitants or goals
Some setups need a tailored approach (deep tank, heavy planting, lots of shade, specific inhabitants). Dimming and spread become more important.

2. Spectrum & colour (Kelvin)

Kelvin (K) describes how the light looks (warm ↔ cool), but not everything about plant suitability. A “daylight” look is often pleasant; what matters is stable output and a usable spectrum.

Kelvin Look When it’s nice
3.000–7.000K Natural / slightly warm A combination within this range is very suitable for planted aquariums.
7.000–8.000K Bright daylight Cichlid aquariums (commonly used), fresh and “clean” look

3. Size & coverage

Even the best light can disappoint if coverage is uneven. Consider tank length, height (depth), and shade from wood/rocks.

Length
Ideally choose a light that covers (almost) the full length for even spread.
Depth (water height)
The deeper the tank, the more light you need to reach the bottom.
Width & beam angle
Wide tanks may need a wider fixture or multiple lights/units for proper coverage.
Mounting
Rim mounts, hanging, or a hood changes spread, reflection and heat.

4. Features that actually help

Extras aren’t just “gadgets” — they make it easier to run stable (and keep tanks looking better).

Dimming (recommended) using a light controller (e.g. NL502)
Start gentler, reduce algae risk, and tune the light to your plants and layout.
Timer / photoperiod (must)
A consistent day/night cycle matters. Many tanks do well with 7–9 hours of light.
Sunrise / sunset (comfort)
Calmer behaviour for fish and fewer “shock moments”.
Water protection & build quality
Splashes and condensation are normal. Look for solid finishing, cable quality and protected connectors.

5. Common mistakes

Mistake Result Fix
Starting too brightAlgae, unstable tankStart dimmed or lower and build up
Photoperiod too longAlgae, stress for fishKeep it consistent (e.g., 7–9h) and adjust gradually
Choosing only by KelvinLooks nice, plants underperformCheck “full spectrum” and real-world results/measurements
Not enough coverageShadows, uneven growthChoose the right length or use multiple units

6. Calculator (estimate)

Not a quiz — just a quick estimate. The result is a range; exact needs vary per tank.

Enter litres to see an estimate.
View aquarium lighting Ask for advice (with photos)

Note: For specific goals (deep tanks, lots of shade, demanding plants), placement, spread and dimming matter a lot.

FAQ

How many hours per day should aquarium lights be on?
Many tanks do well with 7–9 hours. If algae appears, reduce a bit or dim rather than constantly changing on/off. Consistency beats max hours.
Can you have too much light?
Yes. Too much light without balance (nutrients/maintenance) can trigger algae. That’s why dimming is valuable.
Which light colour is “best”?
It depends on your goal. For a natural look, ~6,500K is often ideal. If you want a cooler/brighter look, higher Kelvin can be pleasant.

Want us to take a look?

Send your tank length, height, a photo of the layout and your goal (plants, look, inhabitants). We’ll advise which light(s) fit.

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