# Hydor Theo Heater Help?



## pieleld (Oct 24, 2011)

I recently purchased the Hydor Theo 25W Heater for my 5 gallon (The heater is rated up to 7 gallons). The tank is filtered, with low-to-moderate circulation, but the circulation is decent. This heater operates very strangely, not like any other I have ever used. With it set to 83*°, *it keeps the tank temperature at 79*° *during the day and 77-78*°* at night. Now, the strangest part is that it turns on about every minute (there is an indicator light) and heats the tank for about 20-30 seconds, and then turns off. The heater is CONSTANTLY turning on and off every single 90 seconds. Anyone else have this heater and can give me some advice about it? Not sure if I should ditch it and get the Top Fin 25W at Petsmart for 17.99 (Same Price as Hydor) :-?


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## JahBetta (Nov 5, 2011)

Hydor Theo is a really nice heater from what I have read and I did my fare share of research all over the place before ordering what I wanted.

I am kind of in the same dilemma; it keeps the tank a little above the setting, but I'm not complaining because I live in a cold environment, I actually think it does a relatively good job. But I do have the same question, it seems to turn on every 5-10 minutes, stay on for 2-5 minutes and then turn off again. (I have a 50w on a 7.5g). I thought it was because the tank might fluctuate a bit in the colder weather, however if it is heating as it is and it has been maintaining good temp for my fish, so I am relatively happy with it. Am just curious about the on / off with it as well.

Seems my Betta like it as well, he loves to squeeze in between the wall of the tank and the heater and hide for a couple of minutes before going back to the plants at the bottom=P


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## Draug Isilme (Aug 7, 2011)

I have the same heater (had to buy it for around $21 with shipping- it was the best price at the time but it seems that you found a better deal ^.^) I've never had any problems with this heater at all. It's a 25w as well and it does go on and off, but it's relatively normal as it's making sure it stays at a constant temperature. They're not completely exact, especially when the temperatures fluxuate outside of the tank. I have my heater set to 76 degrees because mine seems to like to be 4 degrees over when temperatures are at its highest and during the day usually stays at 80 degrees- unless it gets colder, which I've notice the temp will lower at night (the lowest it's been is 76, but averagely it goes to 77). You should probably note whether or not the temperature in your house is fluxuating or not- Usually my dad is the one in control of the central air at my house- On average when it's not during winter, the temperature is set from 78-81 degrees depending on the wheather and if it's cost efficient or not to use the air or leave the doors/windows open instead (this is when the tank stays from 77-80 degrees). Otherwise, when it gets colder usually the central air is set from 73-76 and during these cold conditions my tank has been ranging from 76-80 (the wheather's been weird/fluxuating from freezing ass cold to pretty warm/hot which is why there's a larger gap, but once the season settles in, it'll be a constant cold and I'm assuming the tank will range from 76-79). If you notice the pattern with the temperature changes of the house, which is usually 3 degree incriments no matter the season (and yes I have been paying CLOSE attention as it gets too hot/cold for me and I check to see what it's on >.<) the heater is staying about the same.
So yeah, just check on your house temperature, as well as the temperature outside, and start comparing those results to the temperature of your tank for a period of time so you can see whether or not it is from outside influences causing your tank temperatures to fluxuate ^.^ Since there's not really much of a change and it's usually warmer during the day than it is at night (last time I checked anyway, lol), it sounds like your central air is set for a constant temperature and just like your heater, it'll turn on and shut off when need be, but won't stay exactly at that constant temperature the whole time since the wheather outside of the house effects the house as well xD lol....
If it's not that, then.. sorry, I'm not much help there >.>;;;
Sorry for the long explanation, I couldn't think of any other way to get the point across without explaining my experiences with the heater >.< I hope this helps and isn't confusing!

Edit: Also! The heater is only a 25w that's mainly for tanks from 2-7 gallons. Your tank isn't the highest gallon you can have for this heater, but pretty high, so I can see why it would need to turn on and off pretty often. If I understand heaters and wattage correctly, had it been a 50w in your 5g or higher, then it would take less time to heat the tank and shut off until a certain time period when the temperatures begin to drop and basically go like clockwork just like the 25w.


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## pieleld (Oct 24, 2011)

Thanks for the response, generally the temperature does fluctuate in my dorm room, because the heat is user activated without a thermostat. I have to actually turn the heat on and off to control the temperature. At night the room gets really cold. Setting that aside though, it shouldn't even matter with a quality heater. The outside temperatures may effect the water temperature, but the heater is thermostat regulated. It should maintain a constant temperature regardless of fluctuation. I actually do own a Top Fin 25 W heater in my other tank. The heater turns on about every 8 minutes and heats for about 2 minutes. The temperature is always constant to whatever I set it on the heater. Amazon is sending me a new Hydor, hopefully this one was just defective. I have it set at 83 and I wake up in the morning with a 76 tank. During the day it can get it up to 78-79. I'll update this thread when the new one arrives.


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## Draug Isilme (Aug 7, 2011)

Huh, that's interesting. I've never had any other heater, so since it hasn't been a huge deal for me, I haven't really been worried about it. I did a lot of research into the heater and had recommendations- would've sprang for a different kind of heater, but the other one I was looking at ended up with a REALLY, really bad review that had to do with it exploding in their turtle tank ;; while all of the reviews for Theo's from various sites said the main problem was it being defective- even so, I figured every manufacture has it's own defective products every once in a while and the heater still kept an average rating of 4 stars. But hey, just goes to show that you never know what's gonna work for you until you get your hands into it yourself, regardless on how much you research. I just might consider buying a top fin heater in the near future


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## pieleld (Oct 24, 2011)

I also bought this heater based on reviews. There were a few reviews that mentioned this 25W heater maintained constant temps in their 10 gallons. That impressed me. Apparently the one I got was defective. No big deal, I get a free replacement, shipping covered and all. The Top Fin heater has terrible reviews if you read them. Average 2.5/5. IME though, it's a really great reliable heater. Only had it for a few months though.


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## Draug Isilme (Aug 7, 2011)

I probably shoulda did that, too, but I'm guessing it's too late, now, since it's been a while. Ah well, so long as it doesn't try to spontaneously combust in my tank and I feel that I at least get my moneys worth >.>; I believe what I originally thought was since the reviewers said constant, and as I've explained with my situation, my temperature is a constant it just comes with the added variable of outside influences xD On a lighter note, I kinda like to view it as climate training for my fish/snail, lol.. The temperatures aren't changing at a fast rate, nor are they too low or too high and if my heater fails me, their bodies will be more prepared to endure the temperatures a bit more while I run my ass out to buy a new heater before it gets way too cold... Not sure how accurate this theory is, but it makes sense >.>...


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## pieleld (Oct 24, 2011)

JahBetta said:


> Hydor Theo is a really nice heater from what I have read and I did my fare share of research all over the place before ordering what I wanted.
> 
> I am kind of in the same dilemma; it keeps the tank a little above the setting, but I'm not complaining because I live in a cold environment, I actually think it does a relatively good job. But I do have the same question, it seems to turn on every 5-10 minutes, stay on for 2-5 minutes and then turn off again. (I have a 50w on a 7.5g). I thought it was because the tank might fluctuate a bit in the colder weather, however if it is heating as it is and it has been maintaining good temp for my fish, so I am relatively happy with it. Am just curious about the on / off with it as well.
> 
> Seems my Betta like it as well, he loves to squeeze in between the wall of the tank and the heater and hide for a couple of minutes before going back to the plants at the bottom=P


I wouldn't be worried that it turns on every 5-10 minutes. My 25W in the 5G turns on every MINUTE. I woke up this morning with water temperature at 76, the heater is set to 83! So far it has been the worst heater I have ever used, without a doubt and I've used over 5 different heaters throughout my fish keeping. Hopefully this one is just defective and the new one they send is actually even somewhat accurate. :evil:


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## Silverfang (Mar 25, 2011)

I have the 25W heater in a 2.5 gal. I had to set it at about 83 or so on the dial, it does however keep the temperature pretty constant, between 79 and 80. And my boy absolutely loves it. Had to pay a bit more, but that's the joys of buying supplies in Canada.


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## JahBetta (Nov 5, 2011)

Yeah I'm not sure. Mine loves it as well, he always swims around it, has his home in a couple swords right around the heater. I can say that it tends to be a couple degrees off. I had to turn it down from 82 to 79 because the temp as around 85.


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## acadialover (Nov 17, 2011)

I have been going through h--- trying to get the heater adjustment right in my 5 gallons. I had 25w visitherms i them and had allot of fluctuation, from 76 to 83. I went to PEtco the other , sucked it up and got 2 Aquen 50 watt. NOw, the temp in both 5 gallon tanks stays at exactly 80, right where I want it !!!! My apt. gets down to about 65 at night, and 68 during the day. I am very happy with these heaters.


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