The MAYIN Digital Aquarium Thermometer & Humidity Meter brings three readings together: aquarium temperature, room temperature and room humidity. If you have just opened the box, the important first step is knowing which number belongs to the aquarium.
This setup guide covers the black MAYIN multi-function meter sold by YoloLife as SKU A004150. It follows the supplied product packaging, including its external mounting instructions. The complete meter stays outside the aquarium; do not put it underwater.
What do the three readings mean?
On the pictured MAYIN display, the readings are arranged as follows:
- Upper left — indoor temperature: the room-air temperature, shown in °C.
- Upper right — indoor humidity: the room humidity, shown as a percentage. This is not an aquarium-water measurement.
- Lower, larger reading — aquarium temperature: the fish tank temperature, shown in °C.
The physical screen labels on this version are in Chinese; the positions above help you identify them. The example numbers shown in product photos are display examples, not temperature or humidity targets for your fish.
How to set up the MAYIN thermometer
- Activate the batteries. Open the battery cover and remove the insulating tab before first use. Close the cover securely before mounting the meter.
- Choose the correct side of the glass. The packaging specifies the outside of the aquarium glass, below the water level. “Below the water level” describes the position on the pane; it does not mean placing the device in the water.
- Attach the meter. Peel away the adhesive backing and mount it in the specified position, with the screen easy to read.
- Let the reading settle. Allow approximately 10 minutes after mounting, as directed on the packaging, before checking the display.
- Read the aquarium value. Look at the lower, larger temperature reading when checking the tank, rather than the upper-left room temperature.
Use the instructions supplied with your own unit if its design or label differs from the version shown here. Do not assume that a similarly named model has the same mounting method.
A simple daily check
Once the meter is installed, make the aquarium reading part of your normal tank check. Note the time and the lower temperature value if you want to keep a record. The room readings provide separate context, but they do not replace the aquarium reading.
For example, the room temperature shown beside the humidity value is not a reason on its own to adjust the aquarium heater. If a reading seems unexpected, first confirm that you are looking at the correct display area and that the meter is still mounted as instructed.
For broader advice on choosing a measuring method or comparing conflicting results, see our aquarium thermometer placement and readings guide.
Battery replacement and size
The meter uses three replaceable CR1225 batteries. Follow the battery-compartment markings when replacing them; the packaging specifies the positive side facing up. Keep loose button batteries away from children and close the compartment securely.
The black body measures 75 × 65 × 10 mm. These are the device dimensions, not a recommended aquarium size.
Common questions before using it
Can I put the MAYIN meter inside the tank?
No. The packaging explicitly prohibits underwater use. It is an external glass-mounted meter, not a submersible display.
Does “0.1°C precision” mean guaranteed ±0.1°C accuracy?
The packaging states temperature “precision” of 0.1°C, but it does not provide a ± accuracy tolerance. We therefore do not treat that label as a guaranteed measurement-accuracy claim.
What if the display stays blank?
Check that the first-use insulating tab has been removed and that the correct batteries are fitted according to the polarity markings. If the problem continues, contact us with a photo of the unit and its label; do not open or modify parts beyond the battery cover described in the instructions.
Find the correct MAYIN model
View the MAYIN thermometer product page for the current listing and full labelled specifications. For help identifying your unit, contact YoloLife and quote SKU A004150.
Product facts and setup steps are based on the packaging supplied for this MAYIN model. Cover readings are illustrative, not recommended fishkeeping targets.