MarinaBetta Fish 8W Submersible Heater - For Fish Tank Aquariums up to 1.5 US Gallons (5 L)

I was very iffy about getting a heater for my betta as I did not want to deal with the nightmare of it cooking my betta which I always worried about. I have my betta in a 2 gallon glass bowl and despite keeping him in the warmest room in our house during the winter and the room being very small. Despite all this his water was so chilly and he was very inactive and not eating much (my betta was always very active and very curious and very hungry). I decided I needed to get a heater and this heater being very small (so as to not take up much room) and being specifically for bettas I figured I'd give it a try. The water is now a toasty 79 degrees and my betta is once again very active, very healthy, and his colors are brighter and his fins flaied out. It took him just a few days to perk up and get back to his normal self after putting in the heater. Now, PLEASE READ THE FOLLOWING. These are very important points.1. Use a thermometer. I used this one: Marina Floating Thermometer with Suction Cup. I got it off amazon and it is small, does not take up much room (just the bottom needs to be subermged) and is accurate. YOU MUST HAVE A THERMOMETER. I highly recommend that one.2. DO NOT USE THIS IN A 1/2 BOWL. Despite it saying it can be used for this in the directions do NOT use this. It will heat the water up wayyy too much and cook your fish. If you are using a half a gallon bowl I am begging you to please upgrade to at least a one gallon bowl. A betta can barely turn a 360 in a half a gallon bowl and they need exercise to stay healthy and well. I recommend at least a two gallon bowl/tank. They are very cheap off amazon OR go to your local craft store and combined with a coupon you can get a glass bowl in 2 or 3 or 1 gallon for less than 10 dollars (check out michaels!), very cheap and your betta will be much happier and you don't have to worry about the cost.3. IF you are using a 1 gallon or 1.5 gallon bowl/tank get a wall timer and set it so that it goes on and off every hour (1 hour on 1 off 1 on etc.). It will get too hot if you do not do this.This works perfectly with my 2 gallon bowl/tank and it would work up to a 3 gallon tank/bowl (ignore the directions) but I wouldn't use it for more than 3 gallons. The way you clean it is to soak it for about 15 minutes or more in a mixture of vinegar and water. Do NOT use soap on it or on anything you put in your fish tank. Soap leaves a residue that will make your fish sick. Using a small amount of vinegar and hot water to clean things works well. When you first put the heater in the bowl/tank wait 20 min before turning on to allow the heater to adjust to the current water temperature and make sure when removing it to unplug it and then leave sometime for it to cool off. To be noted it took about 5-6 hours for the heater to bring my 2 gallons of water to its set 79 degrees.I really recommend this heater and it works perfectly for me. The only complaint I would have is that it is a very small heater and $15 is a little pricey. I have gotten heater for 10 gallon tanks for cheaper. Good product.

This heater is excellent! I've used it for 3 months now. I have a 1 gallon tank and it works great with my beta. He loves it and rests atop it whenever he wants to get warmer.***Important things to know:***This heater does NOT shut off by itself. It says it will reach a preset temperature, but it means the HEATER will set to a temperature, NOT THE WATER! I learned this from another review. This means your water can get hotter and hotter and boil your fish without supervision!WHAT TO DO:I bought a simple $12 timed plug-in safety outlet that has options for 1 hour, 2 hours, 4 hours, or 8 hours. (Simple Touch C30004 the original Auto Shut-Off Safety Outlet, Multi Setting)You also must buy a thermometer! I bought this little one for $2.50 (Marina Floating Thermometer with Suction Cup).The thermometer has an easy to read green range from 70-80 degrees F, which is safe for most fish. Betas like it closer to 80 degrees. My average room temperature is usually around 72 degrees, and the 4-hour setting on my timed outlet always brings the temperature right up to 80 when I see that it's dropped to around 70. I would NEVER recommend using the 8-hour setting on the outlet, but the 4-hour setting is usually perfect to raise the temperature about 10 degrees, and the 2-hour setting will raise the temperature about 5 degrees. (Adjust depending on your own average room temperature)Together, all three of these things have kept my beta happy, warm, and healthy! The only downside (besides the heater requiring a timed-outlet) would be that I think my beta lost some of his tail due to frequent resting above the heater. He's just fine, but his tail looks kind of torn and I thought it may have been due to the heater.Good luck!

I would have rated this heater 5 stars had the company not put so much thought into a deliberately deceptive, albeit technically accurate description.First, and most important to realize, is that this is an always on heater. It has no thermostat, it simply warms up and stays warm all the time. So the statement that it "reaches a preset temperature" is extremely misleading since most will interpret that to mean the water temperature, when in fact it's the HEATER temperature that remains constant. Whether or not it keeps a bowl/tank at a desired temperature depends on the tank size/water volume, temperature of the room, amount of water circulation/movement, other heat sources such as a light being on or off, lid or no lid, acrylic or glass container, heater placement, and so on. All small "Betta" or "bowl" heaters work this way.This is an 8 watt heater. These heaters usually run between 7.5 to 15 watts. If you have need of the higher wattage, it's much better to use two 7.5 than one 15 watt. That way just one can be unplugged if the water temp is too high, giving you a bit more flexibility. They can be safely buried in the substrate, a nice option in some set-ups.This particular heater has a small red LED, which the description states is lit "when the heater is working" a technically accurate but also deceptive statement. It should more truthfully state that the light is lit whenever the heater is plugged in, rather than give the impression the light, and therefore the heater, will cycle on and off. Rest assured, it won't. No matter the temperature of the water, the heater will emit 8 watts worth of heat anytime it is plugged in.Using this type of heater requires careful and ongoing monitoring. An accurate thermometer is a must. You cannot rely on charts/claims as to how many degrees a specific size heater will raise the temperature in a specific size tank, there are far too many variables. Still, these little units can be quite effective, and I do like this one quite a bit. The LED light, though possibly intended as more a marketing ploy than anything else, is actually a nice feature since there may be times you will unplug the heater and it's easy to forget to reconnect ones with no such indicator. The weight is nice, it tends to stay where it's put, thinner/lighter models are easily displaced. On identical tanks they seem to be very consistent.It is entirely possible to seriously overheat a bowl or small tank using this type of heater. That is not a malfunction, it is simply an inherent risk with any always on heater. If the room gets warmer, the water will as well. These heaters do not adjust for any variable, they simply continue to emit the same amount of heat no matter what. That is what most people having problems with them don't realize, and what the cleverly worded descriptions fail to make clear. When the room temperature changes, so does the tank temperature. These heaters merely keep a small volume of water a few degrees warmer than it would be without it. They do not and cannot maintain any tank at a specific temperature, ignore claims of "maintains ideal temperature" as they are patently false. The aquarist has to be the thermostat by matching tank size to heater size (wattage) and continually monitoring fluctuations due to changing room temperature and other variables. These heaters are not for overly sensitive species, but it is probably far better for a Betta to be in water that fluctuates between 75° and 85° than in unheated water fluctuating between 65° and 75°. Bettas are heat loving fish and quite tolerant of even very high temps, which makes using this type of heater less risky but still not foolproof.For around $20 or more, a heater controller can be attached. I have a rack of 9 identical small tanks w/9 of these heaters connected to one power strip that is plugged into a single controller set at 82°. The probe for the controller is in one of the 9 tanks, and this works fine, keeping all of them a steady 82°.A less expensive solution though somewhat less exact, is to purchase a stand alone *dimmer switch (the type with the plug, about $10). You can then do rather fine adjustments usually with a slide, up or down as the temp fluctuates. I have this heater on a one gallon Marina Cubus with dwarf shrimp and a dimmer and that works well.As I stated at the start, the actual heater is nice quality and has proved quite consistent from one unit to another. It performs exactly as it should, and the limitations are not flaws, just inherent with what it is. I'm not certain why the description only rates this 8 watt heater for up to 1.5 gallon tanks, but it's relatively meaningless in any case. Some of the 7.5 watt models are recommended for tanks "up to 5 gallons" which is no more valid- it depends entirely on the sum of all the variables in each individual situation.My only real problem is with what I consider deliberate marketing tactics meant to mislead a purchaser into believing the product is, or can perform, as something it isn't. A clear explanation of just how the unit really works is needed, especially if the company wants to be held blameless for problems caused by misuse.*If interested, I also review the dimmer switch I use.