Theo Aquarium Heater - Hydor

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Theo Aquarium Heater - Hydor

26 Review(s)

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25W - Hydor Theo Heater
SKU: 202170

reg. $19.99

Special Price: $17.99

50W - Hydor Theo Heater
SKU: 202171

reg. $22.99

Special Price: $19.99

100W - Hydor Theo Heater
SKU: 202172

reg. $24.99

Special Price: $20.99

150W - Hydor Theo Heater
SKU: 202173

reg. $25.99

Special Price: $21.99

200W - Hydor Theo Heater
SKU: 202174

reg. $26.99

Special Price: $22.99

300W - Hydor Theo Heater
SKU: 202175

reg. $29.99

Special Price: $25.99

400W - Hydor Theo Heater
SKU: 202176

reg. $33.99

Special Price: $28.99

  • Stuck on high By on 1/19/2017

    This heater won't turn off even at the lowest setting. Tank is at 74 degrees. It's like the thermostat is stuck. Not a good thing when you have hundreds of dollars invested in livestock.
  • Good By on 6/23/2015

    Bought this hydor heater for my water change, this product I good for what I needed very accurate
  • Dont waste your money By on 1/19/2015

    I Bought 2 150w heaters and both are not accurate, turned all the way down one heater hit 85 while the other was over 90, I now only use these heaters to do my water changes, still need to unplug to let them cool down though.
  • it will cook your tank! By on 1/9/2015

    Bought the 300 watt version and even on the coldest setting stays on with the tank temp over 82 degrees. This has been wildly erratic and is less than 10 months old. Unless this is run on a controller, I wouldn't trust it at all. I had expected a better unit from hydor....needless to say, I use it for water changes only and sometimes need to unplug and wait for the water to cool. Worst part is that at times it seems to work as it should....extremely inaccurate at best and a tank cooker at worst.
  • Decent heater for the money By on 12/11/2014

    I bought this heater for a small nano tank and not really impressed with it. It seems to fluctuate a lot even when the room temp is constant. I will upgrade to a better heater later
  • Horrible heater! By on 7/22/2014

    I have had 2 of these heaters break already and have had to call hydor both times and I am still waiting for my other one to arrive. I am planning on buying the Cobalt Aquatics Neo-Therm heater.
  • Broke after 6 months and killed all my fish By on 2/17/2014

    Heater worked great for 6 months on a 55gal tank... then I started loosing fish.. I did a water change and noticed the temp was very high and the heater was still on.... Using a digital thermometer I found the water to be 86 degrees. Unfortunately, I was to late for most of the fish in the tank... I contacted Hydor for a replacement and they wanted me to send the unit in for them repair it. Sorry not worth my time or effort.. they got my $30 this time, but that will be the last $30 they ever get from me.
  • Would not turn off! By on 1/20/2014

    This heater's gauge seems to have stopped working after only a week! It stays on even when I've dialed it up to the maximum and my water temperature is about 10 degrees below that.
  • Keeps temp stable but prone to leaking. By on 12/13/2013

    I have had 2 of these forminternal condensation within the first month.
  • Good Value For 400W By on 6/1/2013

    I have the 400W version - it is the cheapest and most powerful among the heaters I use, but it also gives the biggest temperature swing (almost 2 degrees compared to 0.5 for the others).

    My guess is that the temperature sensitivity is not as responsive, so make sure it is fully submerged in a spot with good water flow.

    For this item, I would not recommend buying a model that is rated for a larger aquarium size than what you have.