Back

Summer Cooling and Winter Heating for UK Reef Tanks

reefsy

reefsy

February 19, 2026

The UK Weather vs Your Reef Tank

UK weather swings between cold snaps and heatwaves, but reef tanks need to stay between 24–26°C year-round. That means planning for both extremes.

Winter Heating

The rule of thumb: 1 watt per litre of total system volume.

Reliable brands: Eheim Jager (£20–35), Aqua Medic Titanium (£30–50), BRS/Finnex Titanium with external controller.

The Two-Heater Strategy

For tanks over 150L, a common approach is running two heaters at half the required wattage each. If one fails stuck-on, it raises temperature more slowly. If one fails stuck-off, the other maintains heat. Set both to the same temperature (25.5°C works well).

Place heaters in the sump if possible for even heat distribution.

Summer Cooling

UK summers are getting warmer. At 28°C corals start stressing; at 30°C+ it's bleaching territory.

Fans (Budget Option)

Aquarium fans blowing across the water surface create evaporative cooling, dropping temperature by 2–4°C. Cheap (£15–40) and effective in moderate heat, but increase evaporation significantly and lose effectiveness during humid heatwaves.

Chillers

Aquarium chillers work regardless of ambient conditions but are expensive (£300–800+), noisy, and power-hungry. Hailea HC series (£250–400) for budget, Teco TK series (£400–700+) for mid-range, D-D DC series for premium/quiet operation.

Most UK reefers can manage summer with fans, keeping curtains closed, and running lights at night instead of during peak heat hours. A chiller is insurance for worst-case heatwave days.

Emergency Tricks

  • Shift the photoperiod to evening/night to remove light heat during the hottest hours
  • Open cabinet doors to dissipate equipment heat
  • Float frozen RODI water bottles in the sump as a temporary measure

Temperature Monitoring

A WiFi temperature sensor (~£20–30) that sends phone alerts above 27°C or below 23°C is the cheapest insurance available.

Browse heaters, chillers, and temperature equipment from UK sellers — chillers are worth buying used as they're built to last.

How do you handle UK heatwaves? Fans, chiller, or something else? Share what works below.

0 replies

No replies yet

Be the first to reply!

Sign in to reply to this topic

Sign in