Equipment · Timers
Aquarium Light and CO2 Timers
Plants and algae both respond to consistency. A timer keeps the photoperiod steady, and can also switch a CO2 solenoid so injection runs only while the lights are on.
What matters most
Built-in vs. separate timers
Many planted-tank lights now include scheduling. If yours does not, a plug-in timer is a simple fix. Check the timer's rated load against what you plug into it.
Coordinate CO2 with light
In injected tanks, many keepers start CO2 an hour or so before the lights come on and stop it before lights out, so levels are up when plants need them. Adjust around your livestock.
Check before you buy
- Does your light already have a reliable schedule?
- Is the timer rated for the device's power draw?
- Will it keep its schedule after a power cut?
You can skip this if…
Your light has a dependable built-in schedule and you do not run a CO2 solenoid.
Ready to choose?
We have checked 10 timers options for identity, specifications, and fit. Compare them, with what each needs and who should skip it, here:
- Best Aquarium Light Timers and Smart Plugs (2026) (buying guide)
