LIGHTING & CO₂

Lighting Timer

Schedules the photoperiod and switches CO₂ so the two stay in step every day.

Maintaining stage Lighting

Unplug before servicingHands out of the water firstDrip loop on every cableTest before you dose30 ppm CO₂ ceilingCycle before stocking

Lighting

Specification
Type	Mechanical, digital or app
Channels	1–4
Minimum interval	15 min mechanical / 1 min digital
Rating	Mains 230 V, 10 A
Battery backup	Digital only
Ramping	App-based with dimmable lights

Technical parameters
CO₂ lead time	1–2 h before lights on
Photoperiod	7–8 h for high-tech
CO₂ off	1–2 h before lights off
Refugium cycle	Reverse of display
Ramp duration	15–30 min
Drift to watch for	Mechanical timers lose time

Plants and algae both respond to consistency. A photoperiod that varies by an hour or two a day, or a CO₂ supply that comes on at a different time each morning, produces the same result as a badly tuned tank: unstable growth and opportunistic algae.

A timer removes the human variable. The essential schedule is: CO₂ on 1–2 hours before lights, lights on for 7–8 hours, CO₂ off 1–2 hours before lights off. A second channel for the refugium light, if fitted, runs on the reverse cycle so it consumes CO₂ at night rather than competing for it by day.

Mechanical segment timers are adequate and immune to network outages. Digital and app-based timers allow ramping and sunrise simulation, which is gentler on fish and lets a dimmable fixture start at low intensity. Whichever you choose, the requirement is that it holds its schedule without intervention.

Safety and welfare

Keep timers and power strips out of the cabinet floor, where spills collect. Mount them on the cabinet wall.
Check the current rating against the fixture. High-output LED drivers can draw more than the label suggests at startup.
Do not daisy-chain timers. One timer feeding another is a failure mode waiting for a stuck relay.

Using it well

Set CO₂ on the same timer channel logic as the lights, offset by two hours — or use a two-channel timer so the offsets are exact.

Photograph your timer settings. After a power cut, mechanical timers silently lose their schedule and the tank runs on a random cycle.

If you work late and want to see the tank in the evening, shift the whole window later rather than extending it. Duration matters more than time of day.

Controls

LED aquarium lightCO₂ regulator solenoidRefugium lightAir pump

Worth knowingConsistency of schedule is the single cheapest improvement to a planted tank.

Note. Parameters are conventional ranges across the category, not the claim of any one manufacturer. Nothing on this page is for sale and no outcome for any plant or animal is guaranteed. Simulator output elsewhere on this site is a simplified model, not a measurement — confirm everything with a test kit and the equipment's own instructions.

Lighting Timer

Using it well

Controls

Works alongside