# Hydor THEO



## carbonxxkidd (Oct 30, 2012)

Has anyone had any bad experiences with these heaters? I just bought two 50w heaters to use in 5g tanks.

I was so excited when I received them today, because my 5g had a Tetra preset heater before that was only keeping the tank at 76F and I'm excited for it to be up to 79-80. I put it in the tank and plugged it in, and now I have to leave so I won't be able to watch the temp. I'm scared now, because I will probably be gone for at least 4 hours and don't want to cook my fish! I have the dial set to 79 right now, and it is heating (as it should because the tank is only at 76 right now) but need some reassurance that everything will be fine, lol. Or I might just put the old heater back in until I can keep an eye on things...


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## LebronTheBetta (Apr 23, 2012)

Hydor THEOs are one of the best heaters around... Your heater should be fine. I have 2, actually. A 100 watt and a 25 watt. I'm content with it, it will heat to the desired temperature in less than 24 hours.


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## carbonxxkidd (Oct 30, 2012)

Is it normal for it to heat in short bursts of like 10 seconds? Lol, I haven't left yet and have been watching it...temp doesn't seem to be doing anything yet but heater keeps turning on and off.

I'm actually wondering if I got the right heater - it's a Hydor and Amazon said it was the Theo but the heater itself, box and instructions don't say Theo anywhere...


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## aemaki09 (Oct 23, 2012)

The only reason it should be turning on and off like that is if it's at the desired temperature. It'll turn off when its at the temp and turn back on when it gets any lower.
Give it a couple days and keep a close eye.


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## LebronTheBetta (Apr 23, 2012)

Hm.... Mine always turns on and off if it's going to start heating colder tanks. It just needs breaks I guess. Is yours adjustable? It should say THEO.


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## pittipuppylove (Feb 23, 2012)

I've been less than thrilled with all three of mine, actually. They work ok, but the thermostats on the ones I have seem off to varying degrees - there's one that was set to 87* and still only went to 75* before shutting off. I agree with aemaki to keep an eye on it for a couple days


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## carbonxxkidd (Oct 30, 2012)

Yes it's adjustable.








That's it. On Amazon it was listed as Hydor USA Theo 50w.

I guess we'll see when I get home. I bought this because I had heard good things about the Theos and it was small, 7" long. If it really sucks I will return it and try to find something else I guess. It's hard to find heaters that are short though.


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## maycausedeath (Jan 29, 2011)

I had the 25 watt version and absolutely loved it - until it sent the temperature to 92F when it was set to 80. The months when it worked were great though, it's small and quite attractive for a heater. I'm hoping it was just a dud because I'd like to buy another, good luck with yours!


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## carbonxxkidd (Oct 30, 2012)

Well, I just got home and my tank thermometer is reading 79! Hopefully it stays right there.


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## Gryphon (Aug 24, 2012)

I have 3 of them, and while I have had my problems, I would have to agree with the fact they're one of the better adjustable heaters out there. I have the 25w, one of which works perfectly. The other 2 are always slightly off of what it is set at (~3 degrees), but nothing unmanageable. Just make sure you have a good thermometer and keep an eye on things.

The biggest issue I had was that when I first got one, it worked for 2 days and then stopped heating. I exchanged it and now the replacement is the one that works perfectly.


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## Silverfang (Mar 25, 2011)

Gryphon said:


> The other 2 are always slightly off of what it is set at (~3 degrees), but nothing unmanageable. Just make sure you have a good thermometer and keep an eye on things.



I have two as well, a 25W and a 50W, both work great. And both of which are slightly off in their readings. Still, I wholeheartedly recommend them!


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## MSG (May 8, 2012)

*Wondering if the people who actually own this HEATER....*

Let me know what country your HYDOR was manufactured in. 

The 50W & 100W Hydor's in my possession have the GREY colored temperature knob & says "MADE IN ITALY".

I'm not sure if the NEWER style Raspberry colored knob heaters are from difference manufacturing sources.

Same thing applies to all my Visi-Therm 25W-75W heaters. All are "MADE IN ITALY".


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## aemaki09 (Oct 23, 2012)

carbonxxkidd said:


> Yes it's adjustable.
> 
> 
> 
> ...




This is definitely a theo. if that becomes a constant problem I'd call the manufacturer and ask what is wrong and for them to replace it


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## carbonxxkidd (Oct 30, 2012)

As of this morning, it's still reading a perfect 79F, so I'm thinking positive. My fish definitely seem to like the warmer temp, that's for sure.

MSG I'll have to look when I get home (at work right now). It did say on Amazon that it was "Hydor USA" but I'm not sure if that means it's made in USA or not.


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## happypappy (Apr 5, 2012)

I have 3 of these --- keeps my temps steady and have had no problems. I keep the 25watt in my 2.5 and 3 gallon tanks and the 50 watt in the 10 gallon


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## carbonxxkidd (Oct 30, 2012)

MSG, just checked, and it says Made in Italy. 

Temp is still holding at 79.


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## AyalaCookiejar (Nov 20, 2012)

A 50watt IS slightly large for a 5 gallon but still works. Some people have even used the 25watt in one gallon tanks with no issues...

I have 3 25watt Hydor theos for my two 5.5 gallons and my 4 gallon and I have a 50watt for my ten gallon and have had no issues. However, right now, the room temp is pretty cold so all of mine have to be set to about 81 for the temp to stay at 78-79. I don't expect them to stay at EXACT temp because my room temp fluctuates a lot at night. Actually, when my room temp dropped 10 degrees the tank temps only dropped about 2 degrees. All in all, I like them. I would not have bought 3 more if I wasn't satisfied with the first one


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## carbonxxkidd (Oct 30, 2012)

I got the 50w because I had read that the 25w can sometimes have problems keeping up if the room is too cold. These 50w heaters were the same price and size as the 25w, so I figured I'd just go with the 50, that way it doesn't have to work as hard. Right now my house fluctuates from about 66-69F, and I want my tank to be at about 79-80F. It seems to be working great so far, but it's only been about 24 hours, haha. I'm glad I bought two though, so I have a decent heater for my new tank when it gets set up. 

Does anyone know in general how long these heaters last?


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## AyalaCookiejar (Nov 20, 2012)

Not me... My 25watts kept both tanks at 78 when the room temp dropped to 60. Also, I'm not sure how long they last... I've read a few people who have heaters for 3 years or longer, and some seem to crap out a lot sooner. The thing with the Theos is that they have a special setting where the heater shuts off if its not submersed far enough.

I've read many more posts where heaters have broke because someone forgot to unplug them before doing 100% changes than I have where the heater itself malfunctioned. However, that being said, its not impossible. Sometimes you may get a lemon that either doesn't work properly right off the bat or it malfunctions shorty after getting it. One thing I always make sure to do is let the heater sit in the water for awhile before I turn it on so it kind of "adjusts" to the current tank temperature.


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## carbonxxkidd (Oct 30, 2012)

Good to know! I'm hoping because I got a decent quality heater that it will last a while


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## Silverfang (Mar 25, 2011)

I've had my 25W for over a year now.


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## majesticstorm (Dec 8, 2012)

When I first used mine, it didn't heat the tank up to the temperature I wanted it to. I woke up the next morning to see the temperature to be just barely over 70F. I wasn't too thrilled. Thank goodness my boy still seemed fine with the low temperature and was still swimming around happily. But now after a few weeks it seems to have stabilized and keeps my tank at around 77-79F, and so now I'm quite satisfied with it


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## AyalaCookiejar (Nov 20, 2012)

Another thing I like about it is that its good at gradually heating a tank so its generally pretty safe to add it to a tank that already has a Betta in it... I still increase it by like 4 degree intervals a day, though.


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## MSG (May 8, 2012)

They should last 5-10 years under normal use. Possibly longer.

I have one brown submersible heater, that's got to be manufactured in the 70's or 80's. It's 50watts, still works. Hard to adjust the temperature setting though.

Just make sure you UNPLUG the heater every time you siphon water JUST as a precautionary measure from accidentally cracking the glass.

The Visi-Therms & Hydors I got from Stephanie are probably 10 years old. 

Good to know the new Hydors are still Made in Italy.


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## PaulO (Aug 13, 2012)

I have had a 50/50 experience with them, I use a 25 watt on a grow tank and used to have a 50 on my ten gallon. The 25 watt is good and stays near the desired degree at 1.5* difference. Sadly that was not the case with the 50, there was an ich outbreak in my tank and I consequently raised the temp to 86*F. From that point it would always stay stuck at 86 when it was supposed to heat at 76 as well as there was water in the heater when I first got it which may have contributed to it's failure. I recently switched from Hydor to Ehiem and I am not disappointed. Also what is cool about those heaters is they 2 rings you adjust, with that you can manually calibrate the heater so you never have to compensate by turning the temp past or behind the temperature you want to get the desired heat. Also the heater stays accurate to about .5*F . I would say for a heater the Hydor is a good brand and I am not trying to rip on it as I am more than satisfied with it's performance in my 5 gallon it's just that one experience that soured my liking for that company. However I will say they have GREAT customer service, I contacted them and they told me that if amazon would not accept the broken heater then they would gladly exchange it for a working version, oh and it has a classy look to it as well ;-). 

P.S. Mine also flickers on and off sometimes just while it's heating and the light will flicker sometimes too.


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## Fishybitty (Dec 29, 2012)

I keep hearing people talk about these heaters. I might have to check them out because I have a preset tetra also, Mine is keeping at 77 degrees.


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## NorthernLights (Mar 2, 2012)

*love the theo*

My 25 watt Theo (which has a grey knob, btw) worked great in my 1 gallon quarantine tank (which probably had a bit less than a gallon in it), and works fine in my 3 gallon. I've ordered a 50 watt for my 3 gallon so that I can keep the 25 watt for the hospital/quarantine tank since its working VERY hard to keep the 3 gallon at a toasty 80-81 degrees F this winter. I live in a cold area, however, and I like to keep my place cold.


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## callistra (Jun 29, 2010)

I had really bad experience with these heaters.. VASTLY different than setting, won't hold temp.. etc. Finally gave up with them. I'm not the only one.. lots of comments across the web with this. That said, many people like them and have gotten good ones.

All new heaters should be given a 24 hour test run in similar size container with thermometer and no fish to make sure it will keep a constant temp, not overheat or swing. 

You got lucky.. but glad it's working for you 

I like Aqueon Pro (black ones not the glass regular line) Jager and Marineland Visitherm, personally.


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## AyalaCookiejar (Nov 20, 2012)

NorthernLights said:


> My 25 watt Theo (which has a grey knob, btw) worked great in my 1 gallon quarantine tank (which probably had a bit less than a gallon in it), and works fine in my 3 gallon. I've ordered a 50 watt for my 3 gallon so that I can keep the 25 watt for the hospital/quarantine tank since its working VERY hard to keep the 3 gallon at a toasty 80-81 degrees F this winter. I live in a cold area, however, and I like to keep my place cold.


Actually, I have three 25 watts, two have white knobs and one has a red knob... I'm still not sure why.

And I must be lucky x4 because all of my Hydors work great.


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## carbonxxkidd (Oct 30, 2012)

The one I am currently using is still heating my tank at 79...it's only been 4 days but I'm pretty happy with that! I'm expecting to get my new 5 gallon tank this week and I will test the other Hydor heater I bought in there before adding fish.

I tried an Aqueon 150w(not a pro) in my 29g...put it in the tank and it immediately had water inside the heater...I didn't even get a chance to plug it in. I ended up getting a Fluval M150 instead and am happy with it. I have heard good things about the Aqueon Pros, though.


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## callistra (Jun 29, 2010)

The regular aqueons are crap, I agree. The pros are so different. I don't get why they can't make a decent regular line heater, even if it's not as well made.


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## kfryman (Nov 7, 2011)

My Aqueon Pro Heater failed before one year and they have a life time warranty. I don't feel like trusting them with my fish's lives. Ehiem Jagers are the best you can probably buy and on Amazon they are like $25-30, instead of like $60 at Petsmart/co. You can see it in the picture. The problem is is that it failed when it got cold. I am lucky I had the Ehiem already, or my fish would have froze.


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## geopa (Sep 27, 2012)

Have a Hydor 25W for a Fluval Spec V, so far (2-3 months) it has held a steady temperature


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## finnfinnfriend (Feb 3, 2012)

Glad the heater is working nicely!

There's nothing bad about putting a 50 watt in a 5 gallon, is there? I had a 50 watt in my 5 gallon for about 9 months and it was fine, it just stopped working right after that 9 months because it wasn't very good quality...It didn't hurt my fish though...I thought a 50 watt was a good size for a 5 gallon...


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## callistra (Jun 29, 2010)

My 5gs all have 50w


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## AyalaCookiejar (Nov 20, 2012)

My 50watt is rated for 7-14 gallon tanks but it would be fine in a five gallon as long as its adjustable. I've seen some people successfully use the 25 watt rated for 2-7 gallon tanks in a one gallon.

Edit: plus it is convenient if you plan to upgrade to a larger tank later on.


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## BettAsha (Oct 26, 2012)

OMG I love my 25W Hydor THEO its pretty good I agree probably the best heater I've owned. I use my in my fave gallon set up for my dorm room. Always keep things at a nice 78 degrees plus it adjustable.


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