Resun Sunlike 50 is a submersible thermostatic heater for aquariums up to 50 litres. Power is 50 W. According to the description, it has a quartz housing with a two-layer coating, is shockproof and sealed, and is fully submerged during operation. The thermostat switches heating off when the water reaches the set temperature and back on when it drops. An indicator shows when it is working.
What the manufacturer claims
Resun describes the Sunlike 50 as a device that maintains the right temperature for the aquarium's inhabitants. The focus is on a robust housing and automatic temperature control without the owner's involvement.
Key specifications
| Parameter | Value |
|---|---|
| Type | submersible thermostatic heater |
| Power | 50 W |
| Aquarium size | up to 50 L |
| Housing | quartz, two-layer coating |
| Protection | shockproof, sealed |
| Indicator | yes |
| Temperature range | not stated in the listing |
| Barcode | 6933163302756 |
Pros
- Automatic. Holds the temperature by itself.
- Fully submersible. Can be mounted horizontally or at an angle.
- Robust housing. Quartz with a two-layer coating.
- Indicator. You can see when it is heating.
- Right power. 50 W for tanks up to 50 L.
- Sealed. Built for continuous use underwater.
Cons and what to watch
- No temperature range. It does not say what range it adjusts over.
- No thermostat accuracy. The tolerance is not stated.
- No length or dimensions. Important for shallow tanks.
- Description errors. Typos and mixed languages.
How to choose the power
A common rule is about 1 W per litre of water in a room at normal temperature. 50 W suits a tank up to 50 L. If the room is cool in winter or the tank stands by a window, the power may not be enough to keep a high temperature — then choose a model with some headroom.
How to install it
Fix the heater with its suction cups in a spot with good flow — near the filter outlet or an air stone — so warm water spreads quickly through the whole volume. Do not lay the heater on the substrate or bury it: water must flow around the housing on all sides. After submerging it, wait 15–30 minutes for the housing to reach water temperature before plugging it in.
Safety
Never switch the heater on outside water — the housing can overheat and crack. Before water changes and tank cleaning, unplug it and let it cool before taking it out. Make sure the water level does not drop below the heating element during water changes.
A thermometer is a must
The built-in thermostat holds the temperature, but dials are often inaccurate. Put a separate thermometer on the opposite side of the tank from the heater and check it for the first days after setting. Most tropical fish do well at 24–26 °C, but exact needs depend on the species.
If the tank is small
For nano tanks of 10–20 litres, 50 W is more than needed, and with an inaccurate thermostat the water may overheat. For such volumes a compact heater is better, such as the AquaLighter aHeater Mini 10 W.
Aeration and warmth
The warmer the water, the less dissolved oxygen it holds. Aeration helps in a warm tank — for example, the Resun AC-9600 air pump for small volumes.
Signs of a fault
Check the thermometer regularly. If the water is noticeably warmer than the set temperature and the indicator stays on constantly, the thermostat may have stuck — such a heater is dangerous for fish and must be switched off at once. Cracks in the housing, water inside or condensation also mean the heater should be replaced. Keeping a spare heater is wise if you have valuable fish.
Who it suits
The heater suits tropical aquariums of 30–50 litres that need a stable temperature without daily adjustment. Other equipment is in fish equipment.
Verdict
The Resun Sunlike 50 is a 50 W submersible heater with a thermostat and indicator in a robust quartz housing for aquariums up to 50 litres. The downsides are that the listing gives no temperature range, thermostat accuracy or dimensions, so a thermometer is essential.
FAQ
What aquarium size is it for?
Aquariums up to 50 litres.
What is the power?
50 W.
Does it have a thermostat?
Yes, it switches heating on and off automatically.
Can it be fully submerged?
Yes, it is fully submerged during operation.
What is the temperature range?
The listing does not say.
Do I need a separate thermometer?
Yes, to check accuracy.
Can it be switched on outside water?
No, that can damage the housing.
