Fluval E 300 Watt Electronic Heater

The Fluval E200 electronic heater has been rock solid in my aquarium. What really sets it apart is the temperature stability and accuracy. Once set, it maintains the water temperature extremely well without noticeable swings, which is critical for fish health. The digital display is clear and easy to read, and I appreciate being able to adjust the temperature precisely instead of guessing with a dial. The heater reacts quickly when the temperature drops and shuts off properly once the target range is reached. Build quality feels premium and well thought out. The protective casing adds peace of mind, especially in tanks with active fish. It also feels safer than traditional glass heaters thanks to its internal safety features. Pros: • Very accurate temperature control • Clear digital display • Stable heating with minimal fluctuation • Strong safety design and quality build • Ideal for medium to larger aquariums Cons: • Higher price than basic heaters • Takes a bit of space in smaller tanks Overall, this is a reliable, high-quality heater that’s worth the investment if you care about consistency and safety. Perfect for anyone upgrading from basic heaters or running a larger, more sensitive setup.

When I upgraded my aquarium from a 25 gallon high to a 30 gallon my old E100 was no longer powerful enough (despite the E100 indicating it was good up to 30 gallons). I purchased a E200 which works great. This is an excellent heater that is easy to set and monitor. Note: the digital display on the E200 that was sent was faulty and so I returned it and the replacement has no issues.

I have been using this product for about 4 months and it has worked great. I got this one compared to the E200 just because it was a buck or two more. I have a 55 gallon Texas Map Turtles / Guppy Kingdom / and some lucky large snails. The E300 says it's made for anything 100 gallon and under so it handles my task well. I have read other negative reviews about this heater from people using tanks over 100 and even 150 gallon and even installing it wrong....if you read and follow directions this will work for you. I like the casing it has around it so no animal or anything can get close to the heat tube. It had suction cups that attach directly to the heat casing and they suction really well. I have not had to move mine at all even though I have 4 ninja turtle climbing and jumping off of it hourly. So structure wise its made pretty well. As far as heating the tank it has met my needs. I know this from a couple things. I also use some old school suction cup mercury thermometers and they are in line with the correct temp readings. Also since I had hatchlings I wanted to raise my temp to 81 instead of the 77 it was staying at (I got it in december the cold months remember) it always kept it at 81 and now that the warm has come and there has been some really nice days I appreciate it even more because it flashes a differerent color and lets me know the tank is higher than the level I wanted it at. I set it for 81 but the sunny day made it a lil higher so it let me know. I clicked it down to 78 and it does the job still. I'm going to buy another one for my 75 gallon tank eventually. I will let you know how it performs for 75 gallons maybe at another time but for a 55 gallon it has worked perfect. It may work well for me because I have a tank 100 gallon and under. i positioned it under the water with just the temp. change click showing a little but you can put it deeper if you like (thats what sh....ahhh never mind) and I also put it in the path of my cannister filter flow out put. Heaters and filter work better with water flow not stagnant. This is what has worked well for me. I also might add I am using a cascade 1000 and two cascade 600's so I have constant water movement in the tank and on the heater. Like I said before water movement helps heating and filtration. For me....

It looks good in the tank especially with the digital thermometer. However, I feel when I first set this up, it felt underpowered in my 40gal. I questioned if I had setup correctly and watched videos. Now it’s working okay. Temperature do range throughout the day. With my ac on, I feel it struggles to keep temp up even though it’s about 12feet away from the ac unit. I’d say, I’d recommend for smaller fish tank.

This review is for the E-100. I ordered this heater for a 20 gallon planted aquarium, containing 2 Angels, a Green Severum, 8 Harlequin Rasboras, 8 Neons, and a Cory Cat (all young small fish, which will be transferred to a 56 gallon column tank in the future). This heater sells for $59 in stores, and $52 on websites, so at $29.95 from Amazon I jumped at it. Besides, it's a pretty cool state-of-the-art item, and I'm a gadget-guy. I was however, slightly hesitant - there are a lot of warnings and caveats about placing it in a high-flow area, and some bad reviews for underpower and malfunction. But as I mentioned - at $29.95, it was too good to pass up. The box arrived from ASAVINGS, packed loosely in a plastic bag, with no padding, (disconcerting, since this product is largely made of glass) and without an invoice or packing slip. The corners of the Fluval box were slightly "bruised", which didn't fill me with confidence. But there was no apparent damage to the heater. I mounted the heater between two AquaClear HOB filters, to benefit from good flow. This places it fairly in the center of the rear glass. As the instructions suggest, I let the heater acclimate to the tank for 20 minutes before plugging it in. After powering up, I set the temp to 76.5 F. The display began in blue, and went green after about an hour, where it displayed 75.0 F. It climbed to 76.0, and remains there, which is fine. I also have two separate/independent indicators in the tank - a glass thermometer, and a digital probe. The glass thermometer reads 76, and the probe reads 77.5 (the probe has always displayed higher for some reason). Thus, I'm confident that the Fluval E-100 is operating correctly. Since it's only been operating for 36 hours, I realize I'm not offering a long term evaluation. There is one shortcoming, which is rather irritating, and is immediately noticeable, for which I didn't deem worthy of 5 Stars - no "On" indicator. I consider it comforting to know if a heater is "On" or not. FLUVAL TAKE NOTE!! ____________ [UPDATE]: After 72 hours, the unit is running perfectly. The display has remained GREEN, and occasionally cycles between 76.0 and 77.0, which is half a degree on either side of my setting. I've noticed it 'wink' up and down by half a degree when it's sensing a change, and then settle on one or the other after 30 seconds or so. This is the actual temperature it's sensing, and is fluctuating due to water flow around the sensor(s). Live plants in the vacinity are 'waving', which is an indication of good flow. I have yet to experience a Low Flow alarm, or a malfunction. ____________ [UPDATE]: On day nine, I noticed the display showing 77.5, which is higher than I'd seen before. It stayed there for awhile, so I decided to adjust it. But it would only flash to adjust-mode when the lever was pushed to the RIGHT (indicating something was wrong). Then it wouldn't adjust to a lower temp, no matter what I did. Total failure. I unplugged it, and plugged in my original heater. I only paid $29.95 for this heater, so I don't feel totaly robbed. This heater will be returned. [UPDATE]: Thank goodness for Amazon's EXCELLENT Customer Service!! They've contacted the seller on my behalf, to resolve the matter. _________ Not recommended. .

First off, I'm a Mechanical Engineer with 31 years of experience and have a considerable amount of experience related to heat transfer. I've also kept aquariums for 36 years and currently have 3. I've had a Fluval E 200 watt heater in a 75 gallon tank for almost 3 years and it's performed flawlessly. I've read tons of reviews stating the low flow warning is a problem, but that warning is an attribute of this heater. Tank heaters are very compact for the amount of heat they generate and must exchange the heat to their surroundings efficiently or they'll burn themselves out. Just imagine grabbing an old fashioned 100 watt incandescent light bulb that's been on for several minutes .... now imagine that it's a 200 or 300 watt bulb! Also think about the fact that the largest portable space heater you can buy and plug into a standard 120 Volt wall receptacle is 1500 watts. That'll give you a perspective of how much energy 200 or 300 watts is. So yes, you absolutely need water flowing over the heater to carry heat off as opposed to it only heating the immediate area and then shutting off. My 75 gallon tank is fully covered and is in my basement which is typically 63 - 66 degrees in the winter and this 200 watt heater has always kept it within 1/2 degree of the 77 degree setting. I've had many different tank heaters through the years and will never buy anything but these again. As many others have said, being able to just glance over and see the green display indicating that the water temp is within 2 degrees of set point is very nice! I literally look at it every night before going to bed and casually glance at it during the day without even focusing on what the temp actually is. I'm sure many have had defective units but these heaters are wonderful when functioning properly. Oh and I put zero value into reviews stating any heater won't work when the operating conditions aren't given. How many gallons is the tank, what's the ambient air temp, is the aquarium fully covered, etc, need to be known to evaluate whether sufficiently sized. Putting a 1500 watt heater in a well insulated 300 square foot room in your house will keep it toasty; putting that same heater in your outdoor shed in the winter ..... won't help much. One last thing, I'm absolutely not a fan of putting a heater that's considerably larger than required in a tank as I've seen advised many times. All heaters will eventually fail and if it fails in the on mode, I don't want to cook my fish. I'd much rather have 2 smaller heaters in a tank than 1 over sized heater. That way if one fails and won't shut off, the other heater either won't come on at all, or will intermittently cycle to make up what the stuck heater can't do. Heaters are designed to work and will last just fine even if they run a majority of the time. In fact many products will actually last longer if they can just run as opposed to "short cycling" as when they're considerably over sized. I have a Clown Loach that's between 8 - 10 years old and I have no intention of allowing a faulty heater to kill it or any other fish under my watch.

I generally don't leave reviews for products, even ones I love, but I wanted to clear up an issue people were having with this heater in comparison to others. The temperature indication is spot on, very accurate. The design is sleek and well constructed. The issue I was having with this unit was not being able to maintain tank temperature in a very cold room, even though I oversized the wattage/gallons ratio by over double the recommended specifications. I believe the shrouding around the glass mildly hinders heat distribution so it is important that this unit gets adequate flow from the filter. I placed the heater directly under my filter return but still randomly had scenarios where the temperature dropped and stayed in the blue, even for a couple days. Then it would rise to green and maintain no problem. What I realized over time was whenever I did water changes or added water, the temperature dropped that night, even if the water added was warmer than the tank water. As the water level dropped over the next few days from evaporation, the temperature rose back up to normal. My hypothesis: If the water level in the tank is a hair too high, there is less disturbance created from the filter return, even though you are still achieving the same turnover rate. Try either lowering the water level in half inch increments until the temperature is able to maintain, or try rotating the heater sideways to achieve more flow through the shrouding. I recommend the first option because turning the heater sideways looks ridiculous with the digital display. I now maintain 77-78 degrees constantly in a 55 degree room and would purchase this heater again. Fluval makes excellent products.

Easy to use (lots easier than the older one we had) and works well in our 75 gal. Long aquarium. Was well packaged and shipped quickly.