Fluval P10 Submersible Aquarium Heater – 10W, Preset 76-78°F for Freshwater & Saltwater Tanks up to 3 Gal, Shatterproof, Fully Submersible, LED Indicator, Durable & Safe Nano Tank Heater

This thing works like a charm! Just plug and play. Ever since I put it in my Fishtank, my little beta fish are so happy and warm. It’s automatically controlled by the thermostat set at the factory. I was a little freaked out at first when I thought of the idea of buying something that was controlled automatically, but no boiled fish yet! They’re warm and cozy and happy. If you’re on the fence about buying this for your beta fish, look no further than this heater. Buy your little beta fish a blanket before they freeze to death. I’ve been using it for about three months now and it’s held up so far. It’s the perfect size to fit into a 3 gallon aquarium.

This is perfect for my 3 1/2 gallon beta tank! Keeps it the perfect temperature for him. His name is Gill.

Edit: It died right at a year in another tank(couldn't let it go to waste). Fluval wants me to ship it on my own dime and pay for return shipping. So it's cheaper to buy a brand new one. Consider this when thinking long term about this heater. First off, I got a DOA. This isn't a big deal, but I should mention it out of the gate. That said, I really do love Fluval products. The heater was purchased for a Fluval Evo 13.5 to replace the glass one that's too long. While the heater is really compact, the suction cup is useless after a week. So it will fall down on top of the return pump. This warped the case of the pump a bit and made it hard to take off and on. I ended up rigging it up with the power cord to keep it from doing more damage. It keeps the water at 80-82°F (26.6-27.7°C) which is really warm for most aquariums. There's no way to change the setting. It will sometimes decide not to work dropping to 72°F (22.2°C) or work too well and jump to 84°F (28.8°C). It may do this in a single day too. This creates a really harsh environment for anything but some hardy fish. Which stinks as this is supposed to be for a nano reef tank. All in all, with the first one being DOA, a suction cup that's worthless, and the simple fact it doesn't do its actual job well I had to rate it a 1 star. I ended up with a non-Fluval brand and now can't be happier.

Works perfect in the spec 3

Ran a little hotter than I’d like for a beta. Added a secondary thermostat and now it works like a charm.

I use these in my 1 gallon isolation tanks for my bettas and they heat the tanks perfectly. No major fluctuations. It stays above 80 but less than 87. I think it could also work for a 2 gallon

I purchased this heater for a 5 gallon betta tank. The heater is set to the temperature they need. It’s a no hassle addition to my tank. Just check the tank’s temperature now and the .

Worked well at first for my 3.5 gallon tank, consistently keeping the water at 78 degrees. Now, after 3 months, the red light never turns green and it's constantly heating the water to 81 degrees which is too high. Did it's job while I was learning the ins and outs of tank life, but now seems like a risk at that temp.

I bought the Fluval P25 submersible heater to keep my betta warm. After just 6 months of use, the heater cracked underwater and sadly electrocuted my betta to death. When I inspected the heater, I found visible cracks in the plastic. I’ve attached images showing the damage. After this incident, I researched online and found multiple reports on Reddit and aquarium forums like Reef2Reef from other users who had similar dangerous experiences with this heater. I can’t post links here, but you can search “fluval p25 heater cracked” on Google and see for yourself. This is unacceptable for any aquarium product, especially when it risks the lives of our pets. Please be cautious and consider safer alternatives.

Excellent

I don't know about its durability and how reliable this product is, but so far so good. It does what's supposed to do and it takes very little space in my 20l tank. Just plug it in and let it do its job.

Excellent aquarium heater. I have a 3.7 gal tank and it keeps it at the appropriate temperature for my betta without any issues. I like it as the temp is set and never has to be adjusted. The heat turns on and off when required. 2 seconds to install it with the 2 suction cups it comes with.

Excelente