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Hydor ETH External Thermal Heater In Line Heater by Hydor

  • $143.99
  • Save $84 (59%)
SKU: HY00019
UPC: 841421000190
MPN: T08203

Hydor ETH External Thermal Heater In Line Heater Description

Hydor ETH External Thermal Heater In-Line Aquarium Heater suitable for all canister filters with 5/8" flexible hosing. No danger of damage if unit is run dry for short period as the ETH will switch itself off before overheating.

  • Hydor ETH - External Thermal Heater fits in line with your filter tubing
  • Reliable, Simple to Use, Extremely Accurate
  • Suitable for Freshwater and Saltwater aquariums

Ideal for tropical fish breeding situations. Temperature control is adjustable between 66-90 deg F. Includes 2 Year Warranty from date of purchase.

Heats with high efficiency and designed to avoid temperature variations caused by poor water circulation. The ETH external In-Line heater uses the advanced PTC system, which is a special polymer sheet, silk-screened with heating ink (like your cars windshield defroster) instead of metal coils.

This state-of-the-art system allows the unit to be left running without water for a short time with no damage. For indoor, in-line use only, the ETH external heater has an adjustable heating control, and a hanging hook for easy placement outside your aquarium. Requires tubing.

300 Watt
5/8" ID
53-80 Gallon Tanks

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Hydor ETH External Thermal Heater In Line Heater Customer Reviews

Richard, Renton WA on 2015/04/19
Hydor 300w Inline Heater - Works Like A Charm!

I bought the Hydor 300-watt inline heater for my 65-gallon Discus tank. Installation was a breeze since the 5/8" barbed connectors fit the 5/8" return line from my Hydor 350 canister filter perfectly. I set the temperature dial to 85-degrees F and plugged in the heater. Several hours later, the water temperature in my tank was exactly 85-degrees. I've been running the heater for a month now, and so far it's working flawlessly. No leaks, burned fish, or clutter in the tank. If you have a smaller tank, then the 200-watt version is more than sufficient. Note that the 200-watt version is available with either 5/8" ID fittings or 1/2" ID fittings (not being sold here), so check your hose size. Highly recommended.

James, Franklin NH on 2015/04/10
Better than Expected

Works perfectly. Ordered 2, hooked up to my Fluval G3 and G6 filters with no issues.

Geo, Angola NY on 2015/02/07
I like it!

It keeps the temps steady and consistent for my 70. Have had it running for over a month now. Keeping a eye on it in case, as another reviewer stated, so it doesn't "cook" my fish. Any heater has the potential to do this IMHO. So far so good. I had a sump with a 200 watt heater. Never seemed to be able to keep the tank consistent. Perhaps it was under powered (my fault). The sump is gone had other issues/problems. That's why I got the inline heater.

Jay, Golden Valley MN on 2015/01/27
Nice with limitations

I have used a lot of these ETH Heaters on my many tanks for years and they work pretty well but have a few minor issues. 1) They work great on Eheim 5/8" and 1/2" green tubing but will reduce the water flow slightly. It will more noticeable for those with 1" tubing. It would be nice if they offered a 1" version as well. 2) The temperature dial has NO clicks or retentions and can be easily changed if you brush up against it. Make sure the heater is out of the way. 3) Make sure you do not over tighten the tubing connection compression knobs as they are thin and can crack over time. I had one break but the company sent me two free ones. 4) They are only supposed to used in a vertical direction. 5) I had one that stopped working heating even though the indicator light would still turn on. I would still highly recommend them but be aware of their limitations. Personally as I usually have two or more on large tanks I like to connect them to a heater controller so they all engage at the same time.

Nathan, Pewaukee WI on 2015/01/13
The best heater made

I have had this heater for about 1 1/2 years and little maintenance has been done to the inside - yet the temp stays WITHIN .2 of selected temp. It is AMAZING.. You hide it under the tank and connect it to the outflow of your canister filter (or pump) and set temp. Done. The only thing you hear is the relay clicking on and off as it heats or stops. The only way they could improve it is to make it a digital readout rather than the dial - still, I have these for my 55, and 4 others, no issues - EVER. Worth the cost when you want to hide as much "gear" and focus on the tank instead.

David, Lancaster OH on 2015/01/06
No problems at all!

I installed the inline heater in about 20 minutes. The install was extremely easy and has worked flawlessly. Again, I read so many reviews about how hard they are to install, didn't work on arrival etc, and I find it hard to believe. I would recommend this product to everyone. I have it on a 55 gal tank and it never varies more than .8 degrees. Great product.

Zeke, Derry PA on 2014/12/08
Hydor 300 watt

Used this on my 80 gallon tank with a 29 gallon wet dry sump. Had it running for about 2 weeks now. Maintains water at very consistent 80 deg. Liked the external application. Didn't want a heater in the tank or the sump. Plus the dial is easy to adjust without placing my hand in the water.

Paul, Union NJ on 2013/03/24
Best out there

I have a 300 watt on the return line on my 80 and a 200 watt on my 37 gal reef. Both heaters work flawlessly and keep the clutter our of the tank or sump.

Daniel, Olney IL on 2013/03/09
Best purchase yet

What more is there? It is easily hidden, and it maintains steady water temps. Easily some of the best money spent on this hobby.

Deborah, Terrell TX on 2012/12/27
Best heater EVER

If you use canister filters, stop reading this review and ORDER this heater. You will be amazed at how easy it is to install and how GREAT it is when you don't have to look at ugly submersible heaters. I removed FOUR submersibles from my 125 gallon tank and installed two of the 300 watt models and they immediately got my temp up to the desired level and is keeping it there. I wish I had known about these sooner and I believe they are the only heater that anyone with a canister filter should consider.

Chris, Brooklyn NY on 2012/10/30
Great Product

Arrived quickly and in great conditions. Set up and running for about a week now with no issues and constantly keeps temp in check. Best heater I've used as water is forced passed the heating element to constantly regulate and measure temp.

Lynda, Macomb Twp. MI on 2012/09/16
Love it

I've had this heater for over a year and it works great. Fit perfect with my magnum350. Even temp all the time.

Scott, Southeast MO on 2012/05/23
Nice Heater

I love this inline heater. No leaks at all in the connections. It is keeping the water at the right temp, and best of all, it is not in the tank.

Greywaarden, Lexington SC on 2011/05/27
Great unit!

Accurate temperature control and eliminates the use of an in tank heater. It was simple to install as well. My only real complaints are it does not come with a hanger and the control knob is too easy to turn... meaning it is easy to bump the temp out of place. Also Pet Mountain has the best price on the net for this model! If you need a reliable heater and love the idea of an external unit, this is your heater.

Don, Fairfield CA on 2011/04/12
Seem great

So far these heaters seem great. They do fit my canister hoses perfectly, Rena xp3 with 5/8" hoses. I've read other reviews stating fit problems so I have to imagine that these were with the other model that does state 1/2" Anyway, these are great for additional heating without cluttering up the tank. Now hopefully they'll do the job for at least several years....

John, Richmond TX on 2010/11/02
Needs better connections

This thing advertises as being for external canister filters, but like others have said, the fittings are too small. There are lots of methods they could use to improve the fitting connections. Disappointing that they didn't bother.

John, Richmond TX on 2010/10/27
Connection Difficult

I received this yesterday and tried to attach it to my Rena XP3 last night. Like others have said, the fitting is to small for the tubes on the canister filter. I used metal hose clamps and will see if that will hold. Seems like they should really rethink the connection method to make it more user friendly. Pet Mountain has great prices but their "saver shipping" is slow. Took 8 calendar days from CA to TX.

Thomas, Hakell OK on 2010/10/17
work great every 1 should uue

i bought 1 for my 55 g tank and am going to get 2 more for my other tanks

Joe, Merritt Island FL on 2010/10/12
Great heater but............

This is a great heater but it really cuts down on the water flow on my Fluval 405.

Daniel, Mims FL on 2010/09/29

The ETH External Thermal Heater is perfect. The temperature stays exactly where the dial is set. No crazy up and down swings. I replaced my two submersible heaters with this in-line heater. It was easy to install, and let's just say I am not the most "handy" person in the world when it comes to installation. I would recommend this heater to anyone with out reservation.

Dave, Mission Viejo CA on 2010/09/11
Excellent heater!

I have had many aquariums and lots of hard equipment. So far, the Hydor ETH-300 inline heater is by FAR the best I have owned. Being out of the tank, there are no worries of fish getting burnt, or glass shattering in the tank, and the heat is spread through the tank by the current of the return, ensuring there are no hotspots near the heater. Highly recommend!

Ray, Queens NY on 2010/08/05

Packed nicely and delivered on time. Thank you.

Doug, Huntsville AL on 2010/05/22
Consistant temperature

The heater works great and keeps consistent temperatures. My only problem with it was connecting it to the outlet hose from the filter to the tank. The outlet hose on my Fluval FX5 is 3/4" inside diameter, this heater uses a 5/8" inside diameter hose. I used a 5/8" (ID) plastic hose, a 3/4" to 5/8" reduction connector and some clamps to make it fit. I'm still concerned about the reduction in water flow because of the smaller diameter heater.

Chhabi, Natick MA on 2010/02/26
Great heater but difficult plumbing with Eheim 2213

Great heater - temp doesnt fluctuate much and best price around ($45 with free shipping). But, I spent few days and few trips to hardware stores to make it fit with Eheim 2213 canister filter. This unit has 5/8 internal dimension for input and output outlet. My Eheim 2213 has 1/2 internal dimension pipes. I had to buy 1 ft of 5/8 pipe, 2 pieces of 5/8 to 1/2 plastic reducer (or coupling) and 6 clamps to tighten things up. Then it worked. I wish they make these heaters with different outlet sizes.

Leroy, Appleton WI on 2010/01/19
what took me so long

i have a 75 gallon tank that had a couple of large Cichlids. over the years , these fish had probably broke 3 glass in the tank heaters. my fish ended up dying , so i started over from scratch in baby cichlids (Oscars and Jack Dempsey). when searching for a new heater i came across this Hydor ETH heater. I was a little worried about using this heater , but it sounded like a great idea. well it worked out great with my eheim ecco 2235 filter . had to get line reducers , but was easy to set up and has been keeping my temp. a steady 77.7-78.5 degrees. wish I would have got this heater a long time ago. now I just hope it lasts as I have only had it for a month. Pet Mountain was the cheapest and had fast delivery. I couldn't be happier with this heater. Leroy

Kany, Mpls MN on 2010/01/12
Great item at the best price!

Awesome price for a 300W inline heater. Best deal I could find and great product!

David, Tacoma WA on 2010/01/04
Excellent product!

This is an awesome heater. No more room taken up in the tank. No more burns on fish. I will never go back to a in tank heater again.

Henry, Leesburg VA on 2009/10/27
Hydor ETH 300 Watt Heater

Awesome heater. Temperature does not vary at all and I keep the tank in the basement where the temperatures get into the 60s.

Bud, Toledo OH on 2007/12/04
Great Heater!

Great heater! Works very well and nice not having it in the tank!

Todd, Ortonville MI on 2007/04/20
Why didnt they think of this sooner?

These heaters are the greatest thing since sliced bread.Clearly the most efficient and accurate heater ever made.I just bought a 300w for my heavily planted 50 breeder to replace a stealth 200w which I thought were the best and safest until now.Temp. only varies .3 Degrees from day(lights on) to night(lights off).Its also a snap to install it takes about 5 min.

Ryan, San Mateo CA on 2007/02/16
never go back

No more eye sore inside the tank and keeps a constant temp throughout the tank.

Tiffany, Greenville MI on 2007/01/25
Best ever

Perfect for larger aquariums, dependable and easy to use