JBL ProTemp S Aquarium Heater - 25 and - 25W

JBL ProTemp S Aquarium Heater - 25 and 50 W is JBL's internal safety heater in its two smallest outputs, for nano and small aquariums.

Key Features

• Thermostat and heater in one unit: Set the temperature on the body and it holds it, with no separate controller to wire in. JBL quote plus or minus 0.5 degrees.
• Quartz glass with a protective guard: JBL build the element in quartz glass and supply a basket around it, which is what stops a pleco or a loach resting against a hot element and burning itself.
• Dry-running protection: JBL state it is protected against running dry, which is the failure that cracks most heaters. It is a safeguard rather than a licence, so still switch it off before a water change.
• TUV tested and sealed to a metre: JBL list it as TUV tested and watertight to 100 cm, which covers the full depth of any normal aquarium.
• The sizes for a small tank: 25 and 50 watts cover roughly 10 to 80 litres and tanks of about 30 to 80 cm long, which is the nano and small community range where a bigger heater would be actively dangerous.

Choosing The Wattage

• The usual rule is around one watt per litre in an unheated room, and roughly half that where the room is already warm.
• JBL band this range by volume. The 25 and 50 watt heaters cover roughly 10 to 80 litres, and the 100 to 300 watt heaters cover roughly 50 to 400 litres.
• When you are between two sizes, take the smaller. An undersized heater runs longer and holds temperature slightly less tightly; an oversized one swings the temperature and does far more damage if it sticks on.
• Work from the tank's real water volume, not the figure on the box. Substrate, rock and the gap below the rim can easily take a fifth out of the stated capacity.
• A heater is only as good as the water moving past it. Still water stratifies, so put it where the filter flow runs over it.

Fitting It In The Tank

• Mount it low and in the filter's flow, horizontally or at an angle rather than straight up, so heated water is carried away instead of sitting around the element.
• Keep it clear of the substrate and off the glass. Buried in sand it overheats locally, which can crack the element or the pane.
• Fit the protective basket and the suction cups supplied. The cups perish in warm water after a year or two, which is normal rather than a fault.
• Keep the whole element below the water line, including any minimum immersion mark on the body. Never let the top of it break the surface.
• Give it fifteen to thirty minutes in the water before switching on, so the glass is not going from room temperature straight to heating.
• Check it against a separate thermometer daily for the first week, then weekly after that.

Heater Safety

• Switch off at the wall before you put your hands in the tank. A heater is a mains powered element sitting in water, and it is the one piece of aquarium equipment where that matters absolutely.
• Unplug it before a water change and leave it off until the element is fully back under water. A heater run in air overheats and cracks, and the crack is what makes it dangerous.
• Quartz glass is tough, and JBL build these to resist breaking, but no glass heater is unbreakable. If the glass is chipped or cracked, switch off at the wall before touching the water and replace the heater rather than using it.
• Heaters usually fail stuck on rather than stuck off, and a thermostat that sticks closed will cook a tank inside a day. That is why an independent thermometer, checked daily, matters more than any heater's accuracy figure.
• Do not fit a bigger heater than the tank needs. A 300 watt element stuck on in a 100 litre tank kills far faster than a 100 watt one would.
• On anything above roughly 200 litres, two smaller heaters are safer than one large one. If one sticks on, the other is not adding to it, and if one fails off the tank does not go cold.
• Use the protective guard. Plecos, loaches and other fish that rest against surfaces will burn themselves on a bare element.
• An RCD on the aquarium's supply is a sensible precaution on any tank with a heater in it.

Heating A Tank Here

• In an air conditioned room a heater has far less work to do than JBL's European figures assume. A room held at 22 to 24 degrees with a tank wanted at 25 or 26 needs very little input, and the heater will spend most of its time switched off.
• The real risk in this climate runs the other way. A tank in a room without air conditioning can climb well past the safe range in summer, and no heater helps with that.
• If a tank sits above about 28 degrees, the answer is cooling rather than heating: more surface movement, a fan blowing across the water, the lid open, a shorter lighting period, or a chiller on a marine or discus tank.
• Warm water holds less oxygen, so a tank running hot needs more aeration rather than less.
• Think of the heater as a floor rather than a target. Its job is to stop the tank dropping when the air conditioning runs hard overnight.

Good To Know

• Adjustable across JBL's 20 to 34 degree range, which covers everything from a cool water tank to discus.
• The 100, 150, 200 and 300 watt outputs are on our other ProTemp S listing, covering roughly 50 to 400 litres.
• Small tanks change temperature fastest, because there is less water to absorb a fault. On a nano tank the daily thermometer check matters more, not less.
• Keep a separate thermometer in the tank and look at it. It is the only thing that tells you the heater is still doing what it says it is doing, and it costs very little next to a tank of fish.