Zacro2 Pack Digital Aquarium Thermometer, Fish Tank Thermometer, Water Thermometer with Large LCD Display,Reptile Thermometer for Fish Tank Water Terrarium

I've had these less than 12 hours but they seem to be working perfectly. I have a huge fish tank with Bettas outside the glass sliding door in the living room. We love to watch them at night, but with the cold weather we have been having here in South Florida I put some foam insulation on the tank to prevent heat loss on the sides, and back. The bottom, top and front were still exposed, so I got an electric blanket to cover the top and front to prevent heat loss, and I stuck an Aiicioo 24 watt 18 x 8 inch Under Tank Heater pad to the bottom. I wanted to raise the electric blanket off the front so that we could watch the Betta and his 7 newborn 'kids', but I was hesitant because I wasn't sure how fast the cold weather would pull away the heat. I also have two immersion heaters in the tank, but with such a large tank I had doubts as to their performance in this cold weather. I placed the probe of one of the thermometers all the way to the bottom and got about 62 degrees Fahrenheit. I then placed the probe of the second thermometer near the surface, just over 12 inches from the immersion heaters and got 89 degrees Fahrenheit. I found it strange that the temperature at the bottom was so low, so I checked the Lutron app on my phone and saw that the switch for the heating pad was off. That was around 1:00pm, so I turned the heating pad on and left it. Around 7:00pm when we came back from shopping I took this picture and the surface temperature had dropped to 87.9 degrees and the bottom temperature had risen to 72.2 degrees, and this is with the front exposed. This is exactly what I needed the thermometers for. Knowing that the temperature would continue to fall during the night, I turned the electric blanket on to prevent heat loss from the top of the tank. As you can see in the picture, papa Betta(I gave mama away because she was eating her hatch-lings) is sitting between the two immersion heaters, even though the surface temperature is at the higher limit of his comfort zone. Bettas tend to reside at the surface so I'm not too worried about the temperature at depth, nevertheless I'd like the bottom temperature to hit 76. The funny thing is that the babies don't seem to mind zipping around in the colder water at the bottom, but they tend to stick mostly from mid-level to surface. These thermometers will allow me to properly monitor the temperatures and only turn on the electric blanket when it is absolutely needed. It's true the thermometers don't have a back light, but light uses up a lot of power, and for the few seconds I'll be looking at the thermometers, I can use the light on my cell phone. Wonderful and simple product and I love that each one comes with two good suction pads. You can't complain at this price.

I use these for pool, hot tub, to check AC temperature, etc. Work good & good value. Battery is easy to replace, but a rather odd size: L44.

I’ve had these for a while and they still work great!!!!! Never had to change the battery. They are easy to use and accurate. I have one on each side of my 125 turtle tank!They don’t have a backlight so they are hard to read when it’s dark, but if you have the room lights on they are easy to read.Giving a 4/5 cause the suction cups don’t work at all for me! I just leave the wires dangling in the corner of the tank unsecured.Also, the wires are really long so you’ll probably have to bunch them up above the tank.

I bought this digital thermometer for my new aquarium after reading online that the external stick on type can be affected by the ambient room temperature. That is the only kind I’d ever used before and they seemed to work OK? But this time, I thought I’d try the digital with the probe that goes down into the water and I think it’s much better. I really like being able to see a digital display of the water temperature. I believe it is very accurate too, because it’s always within one degree at most of the temperature display on the tank heater. I feel much more confident that the water is the temperature it should be. Also, I do recommend spending a little bit extra for the two pack because you can use the second thermometer to test the temperature of new water before adding it to the tank during water changes and top offs. One comment, I wish the cell battery was easier to get out. After using the extra thermometer to test new water I take the battery out of it until I need to use it again. Each time I have to use some sort of little tool like a metal nail file to help me pop the battery out. But that’s a tiny little thing and I do highly recommend this thermometer.

Works well on the fish tank. Let's me know temperature of the water.

The simplicity of these thermometers is nice, with a switch to choose between F & C, and a nice size easy to read digital display. I have only been using these for the last few hours and when I first installed them in a 55 gallon aquarium that is about 3/4 full they were reading within 1 degree of each other at opposite ends of the aquarium (about 4 feet apart). After just a few short hours they were reading the exact same temperature which is nice to see because it shows they are most likely calibrated the same and that the water in the tank is the same temp at both ends considering the heater is on the back side of the tank directly across from one of these thermometers.So far these thermometers are performing well. The suction cups are clinging to the sides of the tank rather nicely. The display unit attaches easily to the suction cup and can be removed really easy if you ever need to change the battery. Yes the battery cover is on the back at one of the ends, but this isn't an issue with how easy it is to remove the cover and install the battery. After using these for a longer period of time, I will update my review.Pros: both units showing same temp in a large tank on opposite ends of the tank, ease of use, installation, simplicity, display screenCons: nothing yet

These are nice thermometers for an aquarium and inexpensive. Their small size allows you to easily hide them if you want them out of sight.