Aquarium Lighting FAQ: Hours Spectrum and PAR
Aquarium lighting drives plant growth and fish coloration but also drives algae when overdone. Low-tech tanks need 6 hours daily at 30-50 µmol PAR; mid-tech 7-8 hours at 80-150 µmol; high-tech CO2 tanks 8-10 hours at 150+ µmol. Spectrum should peak at red 660 nm and blue 450 nm for plant photosynthesis. This aquarium lighting faq from Gensou Aquascaping at 5 Everton Park covers PAR tiers and photoperiods, and this guide answers the 10 questions Singapore aquarists ask most about lighting.
How many hours of light per day?
Low-tech planted tanks: 6 hours. Mid-tech CO2-injected: 7-8 hours. High-tech high-light EI tanks: 8-10 hours. Fish-only tanks need only 6-8 hours for fish wellbeing. Longer photoperiods do not improve plant growth past 10 hours but do reliably trigger algae blooms. Use a smart plug timer at SGD 15-25 for precise on-off scheduling.
What is PAR and why does it matter?
PAR — photosynthetically active radiation — measures light intensity in micromoles per second at the substrate. Tier targets: low light 30-50 µmol, medium 80-150 µmol, high 150+ µmol. PAR matters more than wattage or lumens because plants only use specific wavelengths. PAR meters at SGD 250+ are rare in hobby use; manufacturer charts work for budget purchases.
What spectrum suits planted tanks?
Full-spectrum white at 6500K base with red 660nm and blue 450nm peaks. ADA Solar RGB, Twinstar S, Chihiros WRGB and Week Aqua P series all hit these peaks. Avoid pure 10000K reef-style lights — too blue, plants underperform. Avoid yellow-tinted “warm white” — plants slow and algae thrives. Browse aquarium lighting for current LED units.
How do I prevent algae from lighting?
Three rules: shorter photoperiod, lower intensity, and balanced nutrients. New tanks should run 4-6 hours for the first month while plants establish. Increase to 8 hours over a fortnight. Run a noon-burst protocol — 4 hours low intensity, 2 hours full intensity peak, 2 hours fade. Algae blooms during long photoperiods because plants reach saturation while algae continues exploiting excess light.
Are low-tech tanks limited to specific plants?
Yes. Low-tech low-light tanks support anubias, java fern, java moss, cryptocoryne, vallisneria and floating plants. Carpet plants, red stems and most demanding rosette plants need mid to high light plus CO2. Low-tech is not a downgrade — it is simpler, cheaper and produces excellent natural-style aquascapes.
What about fish-only colour-pop?
Spectrum tuned to fish coloration uses higher red wavelengths to bring out reds and oranges in flowerhorn, discus and bettas. Fluval Plant 3.0 and Twinstar profiles include “fish only” colour modes. For betta tanks specifically, warm 6500K with red boost makes blues and reds saturate visibly within hours of switching.
Do I need expensive controllers?
For low-tech, no — a SGD 15 smart plug on a regular LED works fine. For high-tech and reef, yes — Bluetooth controllers managing ramp-up and ramp-down replicate natural sunrise patterns and reduce fish startle responses. Twinstar, Chihiros, ADA Solar RGB all include controllers worth the SGD 60-200 premium.
How high should the light be above the tank?
Most LED bars are designed to sit 10-30 cm above water surface. Higher mounting reduces PAR exponentially — 30 cm is half the PAR of 15 cm in most units. Mid and high-tech tanks need closer mounting; low-tech can mount higher to spread light across emersed setups too. Pair with steady mounting from tank and cabinet packages.
Does sunlight count?
Direct sunlight on a Singapore HDB window-side tank creates uncontrollable algae within days. Filtered indirect sunlight is fine but rarely sufficient for plant growth. Always supplement with controlled LED. Tanks placed within 1 metre of west-facing windows experience temperature spikes and algae blooms even with curtains.
Why are my plants melting under new lights?
Most plants sold in emersed form melt for 2-4 weeks when transitioning to submerged. This is normal — new submerged leaves regrow if substrate and water column nutrients are adequate. Cut back yellowed leaves, dose Seachem Flourish weekly, and wait. Lighting is rarely the cause; nutrient balance usually is.
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5 Everton Park #01-34B, Singapore 080005 · Open daily 11am – 8pm
