hygger 100W Mini Inline Quartz Glass Aquarium Heater with External Controller, Adjustable Submersible Betta Fish Tank Thermostat for 10-30 Gallon

First off I was NOT paid for this review and it is NOT part of a promotion. I am leaving this review because I wanted to give my assessment with the product.I am using this on my 7 gallon cube tank with a Hugger sponge filter (which has also been great!). The neocaridina shrimp I keep do fine at lower temps but with winter coming I wanted to help maintain a temp around 72 in the tank and our house gets cooler than that (we let the temp in the house get to 65 at night and is never higher than 68 in the winter). This heater has performed perfectly so far. The temp is incredibly accurate on the dial. I check this every week when I do water changes so I know I'm adding new water with the same temperature.I love the compact size. It doesn't take up a lot of space in the tank and being able to adjust the dial without having to stick your hand in the tank is a great feature. I wish more heaters had that feature.The red light does blink a bit before turning a solid red when it turns on but I've had this for almost 2 months now and seen no issues and the temp has stayed consistent. Also, the top suction cup had some trouble sticking at first but it was a bit curled so I worked on flattening it out more and it works just fine. The heater had not fallen off the tank glass once.When buying an aquarium heater it's important to keep in mind the size of your tank, the water circulation and the temp in the tank you are trying to achieve vs the temp of the room. If you have a larger tank than the heater is rated for than the heater will not perform as you want it to. If you have poor water circulation the filter will not move the warm water around and you will have cold spots. If you have the tank in a room that is 65 degrees and you are trying to get the tank temp to 80 that probably will not work out well and you'll need a bigger heater with better water circulation. Remember what you are asking the heater to achieve and be realistic with your expectations. If you bought a small furnace for your large house and tried to have it keep your house warm in the winter with shoddy duct work, it wouldn't happen! An aquarium heater is no different.With all that said I am very happy with my purchase and would recommend this heater. I have been keeping aquariums for almost 10 years so I know a garbage heater when I get one.

This heater easily maintains my betta's 10 gallon fishtank at 79°F and doesn't change its setpoint during power outages or other interruptions. It seems to be well-built and doesn't have any obvious issues or points of failure, so even though it's been only two months or so, I expect this to work well for several years longer. Excellent value for me so far.Bonus: I really like the addition of a red LED to indicate when the heater is below the set point and is actively heating, it's easy to use for troubleshooting and just checking to see if everything is.working as intended

*UPDATE* After purchasing two thermometers (to make sure the temp reading was correct on my first one and that I am fairly assessing this heater's ability to do its job) I have determined that it does heat consistently (my house can be cool at night so I was worried about that) BUT it is not able to heat a 5-gallon tank above 80 degrees. For fun (before I put a fish in of course) I turned the the controller to 86 degrees but the tank temp didn't change even after several days. So I am leaving this at 4 stars but if you need warmer water in your tank I would look elsewhere.PROS:- Good size, able to fit in a narrow spot in my 5-gallon tank- Heats Consistently (80 degrees or less)- External controller with obvious temperature settings- Easy to set up and useCONS:- Not able to heat a 5-gallon tank above 80 degrees (for reference, my house is usually a bit cooler - 67-71 degrees, it's an old mildly drafty house so not really able to be more specific - perhaps if your house is a bit warmer the heater will be able to heat higher since it's not fighting a colder general water temp?)POSSIBLE CON if it isn't doing what it is supposed to do- There is a red light that turns on and off randomly on the controller, I am assuming that it is to show when the heater is on to maintain a temp but I haven't been able to find a consistent reason for it to be on (i.e. it doesn't necessarily turn on just because I raise the temp on the controller so I am not quite sure what it is telling me)*PREVIOUS REVIEW* I have had this heater for several days. I am reviewing now but will come back and update - I have a little experimenting to do. I have a 5-gallon tank, I am just getting it set up, waiting for the water to cycle etc. It is a Fluval Spec V Aquarium so the way it is is made, there is a space on one side of the tank that is separated from the rest of the tank and this is where the filter and foam block and carbon etc. lives. I wanted to get a small thin heater that would fit in that section away from the fish (as opposed to one that goes under the gravel which I had before). In my initial order with the tank I bought a different heater, 25W which was supposed to be great for a 5 gallon tank but even on high it never got warmer than 71 degrees so it was totally useless to me as I need 77-81 degrees or thereabouts thus why I purchased this Hygger mini heater. First of all I like this heater because it has an actual temperature control on the cord so you can choose the exact temp you want - I love that. The water is definitely warmer than it ever was with the other heater BUT this is where the experimenting comes in. I have the heater set at 80 degrees. The thermometer consistently reads 77. Now I am going to get a Betta so 77 is fine but I am a little nervous. Is the water actually 77 and the heater is wrong, or is the water actually 80 and the thermometer is wrong. Either way I don't want to cook or freeze my fish so...I bought another type of thermometer and starting tomorrow the experimenting will commence. I will then come back and update. Wish me luck!