How to Keep Your Aquarium Healthy with the Right Light Timing
Lighting isn’t just about how bright or colourful your aquarium looks—it’s about how long your tank is illuminated each day. An effective lighting schedule helps support plant growth, promotes natural behaviour in fish, and prevents algae outbreaks. Whether you’re running a basic community tank or a high-end aquascape, getting your timing right is just as important as the light itself.
In this guide, we’ll cover how to set an ideal lighting schedule for freshwater aquariums, when to adjust it, and how to automate it for consistency and ease.
Why Lighting Duration Matters
Aquariums are artificial environments, but your fish and plants still rely on day/night cycles to regulate their biological processes. Consistent light cycles help with:
• Photosynthesis in plants
• Fish feeding and sleeping habits
• Preventing algae overgrowth
• Encouraging coloration and activity in fish
Too little light can cause poor plant growth and dull fish colours. Too much can lead to algae blooms and stressed livestock.
How Long Should Aquarium Lights Be On?
As a general rule, aim for:
• Fish-only tanks: 6 to 8 hours per day
• Low-light planted tanks: 7 to 8 hours
• Medium- to high-light planted tanks (with CO₂): 8 to 10 hours
• High-tech aquascapes: Up to 10 hours, often broken into ramp-up and ramp-down periods
💡 Tip: Start with 6–7 hours and increase gradually if plant growth is slow but algae is under control.
How to Maintain a Consistent Lighting Schedule
1. Use a Timer
A timer is your best friend. Manual timers are simple plug-and-play devices that automatically switch your lights on and off every day. Digital timers offer more customisation, including separate weekday/weekend settings.
2. Smart LED Lighting
If you’re using a modern LED system like Twinstar, Chihiros, or EcoTech Radion Freshwater, they may include built-in controllers or app-based scheduling. These can simulate:
• Sunrise and sunset transitions
• Midday intensity peaks
• Moonlight/nighttime dim modes
This not only looks beautiful but helps reduce fish stress from sudden changes in lighting.
3. Avoid Manual Switching
Switching lights on and off by hand is unreliable and inconsistent. Even slight variations can trigger algae, disrupt plant cycles, or confuse fish.
Should I Have a Rest Period?
Some aquascapers recommend a “siesta period”—a midday break where the light turns off for 2–4 hours. The theory is that this mimics natural lighting and gives plants time to process CO₂ without excess algae growth.
This is optional and not necessary for all tanks, but it may help in high-light tanks where algae becomes an issue.
Signs Your Lighting Schedule Needs Adjusting
• Algae problems: Reduce duration or intensity
• Plants not thriving: Increase light slowly or ensure nutrients/CO₂ are balanced
• Fish hiding constantly: Lights may be too bright or on too long
• Faded colours in plants/fish: May indicate either not enough light or too much stress from intensity
Don’t Forget Light Maintenance
Dirty light covers, algae on fixtures, or condensation can block valuable light from reaching your tank.
• Clean light fixtures every 2–4 weeks
• Check timers for accuracy after power cuts
• Replace aging bulbs (if using fluorescents), as output can drop significantly over time
Example Schedules
💬 Need Help with Your Lighting Schedule?
At Charterhouse Aquatics, we carry a full range of LED lighting systems, smart timers, and lighting accessories to help you automate and perfect your setup. Whether you need a timer for a beginner tank or a programmable controller for a custom aquascape, we’re here to help.