fishkeeper 300W/500W/800W Adjustable Submersible Aquarium Heater – PID Electronic Smart Thermostat Fish Tank Heater with Out-of-Water/Run-Dry/Overheat/Low-Temp Protection for 40-220 Gal Fish Tanks
$37.99
Price: $37.99
(as of Oct 12, 2025 10:11:21 UTC – Details)
From the brand
FISHKEEPER • Aquarists’ Trust
Premium materials, precision-built designs, pro-level craft — every step undergoes strict quality control and safety/durability checks.
We protect your aquatic life’s safety as if it were our own.
Your tank’s reliability starts here>>
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Product Dimensions : 11.6 x 2.16 x 1.18 inches; 1.57 Pounds
Item model number : FK016-300W
Date First Available : July 31, 2025
Manufacturer : fishkeeper
ASIN : B0FFS5QBXB
Best Sellers Rank: #61,800 in Pet Supplies (See Top 100 in Pet Supplies) #160 in Aquarium Heaters
Customer Reviews: 4.7 4.7 out of 5 stars 11 ratings var dpAcrHasRegisteredArcLinkClickAction; P.when(‘A’, ‘ready’).execute(function(A) { if (dpAcrHasRegisteredArcLinkClickAction !== true) { dpAcrHasRegisteredArcLinkClickAction = true; A.declarative( ‘acrLink-click-metrics’, ‘click’, { “allowLinkDefault”: true }, function (event) { if (window.ue) { ue.count(“acrLinkClickCount”, (ue.count(“acrLinkClickCount”) || 0) + 1); } } ); } }); P.when(‘A’, ‘cf’).execute(function(A) { A.declarative(‘acrStarsLink-click-metrics’, ‘click’, { “allowLinkDefault” : true }, function(event){ if(window.ue) { ue.count(“acrStarsLinkWithPopoverClickCount”, (ue.count(“acrStarsLinkWithPopoverClickCount”) || 0) + 1); } }); });
✦✦ Accurate Temperature & Ultra-Safe Protection✦ This internal aquarium heater is a fully-electronic high-quality heater. Advanced water sensors and IC chips combined with PID precision electronic algorithm technology make the temperature accurately controlled within ±1℉; Buil-in multiple safety functions: run-dry, overheat and low temperature protection, which can intelligently monitor temperature at any time and give maximum protection, no more worrying about it will “cook” your love fish!
✦✦ Smart Frequency, Rapid & Efficient Heating✦ Adopts high-quality nickel-chromium heating wire to bring an extremely fast heating experience. Its intelligent system auto-adjusts power: Full blast when heating cold water, then seamlessly reduces as it nears your target temperature and constant temperature. This means quicker comfort for your fish and lower energy bills for you – win-win!
✦✦ Enhanced Explosion-Proof Quartz Glass✦ The submersible fish tank heater is made of thickened explosion-proof quartz glass, high-density silicon carbide sand filler in the tube makes the fish tank water heater evenly and effectively prevents electric leakage. The smooth and pretty heat-diffusing shell also protects curious critters from burns and complements your tank’s aesthetics.
✦✦ Crystal-Clear LCD Display & Effortless Control✦ The bright LCD backlight temperature display with indicator lights can clearly observe the working status and water temperature in real-time. External touch thermostat, cyclic 59℉~94℉ / 15℃~34℃ adjustable temperature; ℉/℃ temperature units can be switched, simple to use and avoid wet hands. Comes with 4 powerful suction cups for exchange, can easily and firmly be placed anywhere in the aquarium, either vertically or horizontally.
✦✦ The Right Fit & Worry-Free Ownership✦ Choose the perfect wattage: 300W (for 40-80 Gal), 500W (for 80-150 Gal), 800W (for 150-220 Gal). Features 9.9FT lengthened UL-certified power cord (5.9ft + 4ft), Voltage 110-120V/60Hz. Suitable for freshwater and saltwater tanks. Before being dispatched to customers, each aquarium water heater undergoes our rigorous computerized testing ensure the highest possible precision of operation and top performance.
7 reviews for fishkeeper 300W/500W/800W Adjustable Submersible Aquarium Heater – PID Electronic Smart Thermostat Fish Tank Heater with Out-of-Water/Run-Dry/Overheat/Low-Temp Protection for 40-220 Gal Fish Tanks
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$37.99
P. Wang –
High tech and protected aquarium heater
This is a much more intelligent and high-tech aquarium than any other heater I have used. Because of how many I need, I usually get the least expensive one that has a preset temperature setting so I can forget about it. Unfortunately, some of them fail without notice. This fishkeeper heater has some nice features I’m really like. First it arrived quickly with Prime next day. The unit is quite robust, with a plastic or ABS shell over the glass container – I’m not used to seeing that. It makes the heater bigger but easier and safer to handle. There are attachment holes on the shell for 2 suction cups, and 4 suction cups are included. The glass is supposed to be thickened quartz glass. It is filled with sand to help distribute the heat. What I really like about this heater is the display and the intelligence of the microcontroller. The display shows the current temperature when there are no other issues. Otherwise, it can show either too cold or too hot, and also when it detects it is out of water. There’s an LED that indicates whether the element is on or off. The microcontroller controls the ramp of the heat, so it heats up quickly but ramps down as it reaches the desired temperature. Unfortunately, the full capability of the heater can’t be demonstrated until the weather is cooler. The temperature setting dial is outside of the water on the cord so there’s no need to fiddle with it in the tank. Now for the negative – size. There are 3 models available: 300w, 500w, and 800w. However, their physical dimensions are exactly the same. This means the 300w unit I chose is the same size as the 800w unit for a 200-gallon tank, but I’m using it in a much smaller tank. I would have preferred that the physical size reflect the power output and tank size.
Brian –
Good deal
So far so good. It is actually being used in a baptismal pool the size of a large tub. We don’t keep it on all the time but if I plug it in for the day the water is 80 in a few hours . I would say 200 gallons?
Lindsey –
Iâm switching all my tanks to use these!
When I first got this heater, I thought it was just too big, how could I possibly hide it?. But the glass tube heater in one of my tanks had stopped working without letting me know in any way til I was removing a plant from the tank and felt the chilly temperature of the water with my hand. Not exactly the best way to discover a problem like that. It could have been the death of my aquatic critters. This heater has a few features Iâve never seen on a heater before. I wish Iâd had these options for all my tanks from the start. An adjustable temperature range, a digital thermostat letting you know the current temperature of the water, it will turn off if it detects that it is not in the water, and most importantly⦠I can see that it is working as it should. Because of its size, I had to do a little bit of adjusting of the tank’s decor to make it somewhat hidden, leaving the digital end peaking out from behind the plants, but because it also has a protective outer casing, itâs safe to put some live plants pretty close to it. If you are still using the basic glass tube heaters with nothing more than a tiny red light on the back to say it’s on and have no control over the temperature they boil the water up to, switch to these; you will not regret it, and your aquatic critters will love you more.
Mari Carmen –
Wonderful water heater
Got this heater for our 75gal aquarium. Previous heaters worked well but this one has more features that are really nice. The real time temp monitoring is extremely handy so you’ll know right away if there is a problem that needs to be addressed. It also heated up the water to the desired temperature relatively quickly so that was nice. It has been in our aquarium since we received it and so far, no technical issues- it has worked exactly as intended with no problems. Our fish are doing well and the temperature has stayed consistent. It’s also not super bulky (though it is a little bigger than other heaters we’ve used) and comes with suction cups to keep it in place. I really like that it automatically shuts off if no water is detected and restarts once there is water- it makes me feel a little safer. If it continues the way it’s been going (it’s been in our tank about a month at this point), I suspect it will continue to work as expected for a long time.
Miss C –
Good Thermostat
I’m switching to adjustable heaters in all of my tanks after having some temperature issues. I really like this heater. When I first pulled it out of the box, I was impressed by its size and weight. The instructions are pretty thorough and very simple to understand. It did take me a minute to figure out that it comes with extra suction cups, which was definitely not a bad thing once I realized I wasn’t missing any places after attaching just two of the four. When you set the temperature the heater will temporarily show the temperature you set it to, and then switch to showing the current temperature of the water. I like that I can just glance at it when I go by and know that the temperature is where I want it. My separate thermometer always reads very close to what the heater’s thermostat reads. The heater is bigger and harder to hide than some others, which some people may not like but I don’t mind. You can always add extra plants (real or fake) in front of it if that’s an issue for you. I often find a snail or two stuck to it. Anyway, it’s just been in my 20G tank for a couple of days, and so far so good!
Kathleen –
Nice!
Holy COW!!! This aquarium heater is awesome! I love the way it sorta disappears in the tank because of the black color. I hate those darned silver heaters that stick out like a sore thumb. Nice thermometer that seems to keep the water at a constant temperature. So far, so good.
Amber H –
Great tank heater
Really nice tank heater. Super easy to set up. I tested it in my small tank to make sure it works. Got this for my 75 gallon tank that isnât set up yet. Works great and I really like the adjustable features. My tank stays plenty warm in the summer, but I know Iâll need this heater in the winter to keep my fish warm.