Cobalt Aquatics Accu Therm Submersible Heaters

I purchased this heater in March, and within ONE WEEK, I heard a HUGE explosion! The heater literally EXPLODED like a bomb!! It smelled like a fire, and LUCKILY I was home or else I’m relatively certain the house would have burned down! I contacted Cobablt(the manufacturer) and they told me it was “consumer error” b/c I had a water/air interface when using the heater. The heater was ENTIRELY SUBMERGED the whole time, there was no ERROR on my part! I have two more of these same heaters, all being used the SAME WAY! I submitted a report to the Consumer Product Safety Commission, it was published & then the manufacturer submitted a comment saying I had mis-used the device & CAUSED it to fail! NO, that did NOT happen. Suffice to say, the report on the CPSC website was subsequently removed! I’ll NEVER use one of these heaters AGAIN! Luckily, there weren’t any jellyfish in the aquarium when the heater exploded. Buyer BEWARE!!

I bought this 200W unit based on Cobalt's reputation for qualify fish foods but that obviously does not extend to hard goods. This thing is garbage. The thermostat is extremely inaccurate (off by 6 degrees or more) and the unit only heats in short "bursts" (likely to prevent over heating) making it ineffective in holding/maintaining temperatures in even my small 29 gallon QT tank. Bottom line, I have expensive discus that I am providing critical heating needs for and I can't rely on a product that won't hold temperature and necessitates heat settings 6-8 degrees above actual output. I will be returning this promptly and not buying any further Cobalt hard goods.

Cobalt has such a great reputation but their heaters are a disappointment. I bought this heater in August but didn’t set up my aquarium until the beginning of October. It worked for about 4-6 wk then it died. So I came to amazon and found the same heater at a better price, and because I have Prime, I received it in 2 days. While this heater works , it’s off by 6-7 degrees so I have to monitor it very closely. I have 3 neotherms and they don’t work well either. Temperature in those heaters are 5-7 degrees off as well, so now I’m replacing them with Fluval heaters which have been consistently accurate. I know it’s the heaters that are off because I have 2 types of thermostats in each tank and they agree with each other, but not the cobalt heaters. I won’t be buying any more Cobalt heaters.

These can run a little long lenghtwise, seems to run longer then other heaters for the wattage so be sure it fits your needs with dimensions. It has a dial so you can control your own settings on the heat range, it is accurate. I am running this in my 5 gallon water tubs for water changes.m keeps temps consistent. It says to put it vertically hot horizontally which makes me wonder why, but I follow the rules lol. Sorry about the hard water on the heater pics. I'm using it, had to to make a accurate review lol

Fairly small size for 200 watts. 4 degrees high of what dial is set to. Holds temp steady within a degree exactly, 78.2 on to 79.2 off ( I use a controller that tracks temp) Supposed to have electronics that have low voltage on, off contacts, should prolong life and be consistent in maintaining temp. I have one heater that varies between 2.4 to .5 degrees of set temp, does as it pleases. Reef tanks need stability.Directions do state it should be vertical. It has a rubber boot on bottom to avoid impact breakage. Suction cups hold well. On light is fairly visible.Its fairly busy looking so if you are going to put it in view keep that I'm mind, not stealthy.Its only a couple of weeks old. I will update review if it does something wrong. So far so good.

This heater failed twice. Once after 90 days and then the replacement failed after six months. Not a very good experience. I had to return it for replacement to the manufacturer at my expense ($12 or $13 each time). Additionally, both times I had to call Cobalt and followup on the return as it was not replaced in a timely manner. The turnaround time was about three weeks before I got the replacement. In the meantime, I had to buy a heater locally otherwise all my fish would have died. The second replacement I was sent a newer more expensive digital 150 watt model Neo-Therm. Digital heaters are supposed to be more reliable. BUT, I have since read the AMAZON review by "Calcifer" and the comment by "Utah Bliss" warning about the exploding and smoking Neo-Therm heaters plus the loud clicking noise. I am now concerned I have a ticking time bomb in my home and am shopping for a reliable heater manufactured by anyone but Cobalt. Would I buy this again? NO! I am very unimpressed with Cobalt product's low quality and reliability.

Only been operating the heater for about 2 weeks. I noticed the light was flickering today and smelled a burning smell. I unplugged it and pulled it out of my sump only to find the glass had been broken and it was burnt on the inside. This heater went straight from the box to the bottom of my sump so it was Never plugged in out of water. I have never had problems with cobalt products before and I'm hoping this is just a defective heater. Included photos of broken heater and return area of sump where heater was located across the bottom.*Update* Initially I gave a one star rating but after contacting Cobalt Aquatics about the heater they are going to send a replacement covered by warranty, this was processed in a very timely manner. I will update again as time progresses. I am not giving up on the company yet.

I bought a bunch of these and they worked great.Heated properly.Heated quick enough.Kept temps steady.Color blends nicely with my tanks.Quality build.Priced right.packaged nicely.Shipped quickly.I'd buy again.

The heater is a bit longer than I'd ideally like, but it keeps the temperature it's set at and that's what's most important.