I started a new 20 gallon high recently because I already had some leftover lumber I'd been wanting to do something with and when I saw a 20 gallon high used at the LFS for $15.00 I traded in some old equipment and walked out of there with it for $3.00. The whole point of this aquarium was to be a low budget build using as much existing equipment as possible to get it started. Filtration--air pump and Hydro Pro sponge: check. Wood for DIY stand: check. Lighting and heating? Not so much. I was able to get the Finnex Stingray 24" for around 30$ which was excellent and I was toying with the idea of ordering a heater at the same time to get free shipping.....but my impatience got the best of me so while I went to WalllMart to pick up the same cheapo thermometer I've always used I decided to pick up a heater with it. I'm sure nearly everyone here has browsed through the pet section of that store and passed by the aquarium section, or partition should I say, and seen their limited selection of equipment. Well if you look at the heaters you will notice one thing primarily: usually they only stock the Whispers. And the one they always have there is the HT series of compact submersible heaters. They come in HT10 (10 gallon), HT30 (30 gallon), and HT55 adjustable (55 gallon) varieties. Get a 100 watt super-compact automatic HT30 aquarium heater for $18.00 out the door? No shipping? Yes please.
Unpacking the HT30 box reveals that it has a single suction cup--not great as any sort of movement of the cord will torque it out of place slightly--that is on there REALLY well. Not that you'd have to take it off anyway, but adjusting it is kind of a pain. The cord is on the short side of average length for tank equipment but adequate. The most striking feature of this heater is how compact it is at under 8" long. It would be really easy to hide especially if you had a pair of them in a large tank. I mounted it in the tank upright on the far side back from the filter close to the substrate which could pose a problem of circulation of the heat but I had considered this when I bought a slightly larger wattage than necessary for 20 gallons. The goal of this tank is to keep Bettas so light circulation is a must especially if they end up breeding someday. After a day or so of letting the heater do its job in the tank I checked the temp--77 degrees F--which was well within the +/- 2 degree margin of error. The temp in the house was 75 degrees all the time as it had not quite yet begun to get cold outside. Now that it is constantly around 65 degrees in the house the tank is holding at only 70 degrees so the HT30 is NOT able to do its job. And it is not a problem of circulation as it is 70 degrees immediately around the heater as well as as in the opposite corner of the tank.
Now, here is why I am so disappointed. I of course read the reviews for this heater before I stuck it in the water (but only after I bought it--derp) and the most common and striking failure is a catastrophic structural failure of the glass tube causing it to explode and rain glass onto the bottom of the tank. I was prepared for this physically as the outlet is a GFCI but more importantly I was mentally prepared for this thing to explode. Another common failure is for the thermostat to fail and turn the tank into a giant pot of fish soup. I was prepared for this by only having one fish in the tank and frequently checking the thermometer for signs of overheating. What I was not prepared for was a failure completely apart from anything I had read--the automatic thermostat is calibrated entirely too low from the factory and the good temperature readings I had initially were only because the house temp was identical to what I was expecting the heater to deliver. Now my Betta is sluggish and does not like it, spending most of his time hovering by that garbage heater.
I just caved and ordered my third Marineland VisiTherm. Not a high-end heater by a long shot but at least I know it will function properly and if the thermometer is miscalibrated I can just dial it in with a separate thermometer. I'm getting the 100 watt model delivered to my door for $14.00 total from that one sight named after a South American river so not only is the Whisper HT line garbage (as evidenced by the countless internet complaints logged against these things) but they are wildly overpriced as well. I don't have a receipt but that has never mattered at the BlueMart before so as soon as the VisiTherm shows up I'm going to box up this piece still wet and take it back to the local store.