1 heater OR 2 smaller heaters???

[univmd]

Good evening, I have a question. Should I use 1 heater or 2 smaller heaters?

Most people seem to think that using 2 smaller heaters is better so that if one fails, the other one still works, and so on.

But my local fish store thinks that 1 correctly sized heater is better because 2smaller heaters will cycle on and off more often as they fight each other, or else one smaller heater will work overtime while the other one doesn't even work, more heaters to break, etc.

What do you think is better? Currently I have a 55 gallon tank with one 250 watt stealth heater.

With warm regards, James

[brewmaster15]

Hi James,
Ideally.... If possible 2 smaller heaters is best...If one sticks on you;ll have less th chance of cooking your fish...if one fails...theres still one that can help maintain the tanktemps from going cold to slowly dropping in temp... I do this where I can...but elsewhere I just pray.:)


my local fish store thinks that 1 correctly sized heater is better because 2smaller heaters will cycle on and off more often as they fight each other, or else one smaller heater will work overtime while the other one doesn't even work, more heaters to break, etc. That logic doesn't work for me...each heater has a thermostat...2 heaters working properly should only kick on when the temp drops and should shut off when it reaches set point.

I think the point your LFS is missing is the two heaters are to minimize the effect of one failing where there is only one....often because we run them at high temps that failure is a stick on --cook your discus failure....something that is relatively uncommon for your average trop tank...iMO.

HTH,
al

[alpine]

James, a 250 watt heater will cook those fish pretty good if it happens to stick on.
I had the best quality titanium heaters with high tech controlers in my tanks. Went out for a weekend out of town and came back to see my breeder age females that I separated to a 75 tank at 104 degrees, all dead. From that day I have gone to double simple visitherm stealth heaters of lesser wattage. It is working very well for me .

Roberto.

[RockHound]

IMHO,

2 large watt heaters is better.
Either large enough to do the job alone.

The reason being;
Neither has to work hard.
Or, operate near max capacity.

They seem to last a lot longer, that way.
Plus, with 2, you have a fail safe extra, if 1 dies.
That is large enough to do the job alone.
Still, without running at max capacity.

I have found, running heaters at or near the top end of temp settings.
Is what causes them to stick wide open.
And, cook fish. :o

Just my 2 cents.

[kaceyo]

Two large heaters doesn't make any sense. The ultimite goal is to make things as safe as possible for our fish, not to keep heaters running as long as possible. Fish cost big bucks compared to replacing a heater and we put so much into raising and keeping them besides. With two big heaters you're doubling the chance that one will stick on and kill the fish, while with two smaller heaters, you're eliminating (or close to it) the chance that heater malfunction will kill the fish.
Not to mention that two large heaters kicking on at the same time will heat the water vary quickly, too quickly I think, and create more extreme fluctuations in temp.

Kacey

[ShinShin]

I agree, Kacey.

Mat

[GrillMaster]

Al an Kacey present very valid points! Keep in mind that heaters are the root of all evil in this hobby! They are the most inconsistent piece of equipment we put in our tanks no matter what brand you buy.

So lower the odds of these inconsistencies and use smaller wattage heaters so if anything goes wrong you can usually fix the problem before its to late.

tc
Mark

[RockHound]

Two large heaters doesn't make any sense. The ultimite goal is to make things as safe as possible for our fish, not to keep heaters running as long as possible. Fish cost big bucks compared to replacing a heater and we put so much into raising and keeping them besides. With two big heaters you're doubling the chance that one will stick on and kill the fish, while with two smaller heaters, you're eliminating (or close to it) the chance that heater malfunction will kill the fish.
Not to mention that two large heaters kicking on at the same time will heat the water vary quickly, too quickly I think, and create more extreme fluctuations in temp.

Kacey

I believe there is safety factor in having 2 heaters, either of which is capable of maintaining the desired tempurature by itself.

The reason I say that is, both run at half there capacity.
Given that fact, in my experiance, neither is likely, or apt to stick at full at full capacity, overheat & kill fish.

If that makes any sence.:confused:
Possibly, I am wrong.
But, I have not had a heater overheat & killed fish, like that.

[Discus-Hans]

2 smaller heaters. (=POINT)

It's something I SCREAM now for years, if you don't do it and you run one day into "fish soup" I will kick your a$$ and say "TOLD YOU SO"

Hans

(Who doesn't use heaters at all because you can't trust any of them)

[digthemlows]

I have 2 250 watt heaters in my 125.....:)

[MSD]

Wow Hans, that info will just "change the discus world". :D

[wgtaylor]

James 250 watt heater in a 55 gal aquarium should be fine until it fails (it will).
I no longer have a dedicated heated fish room so heating aquariums is a source of frustration for me . Use one properly sized heater you will have all or nothing. Two heaters will give you back up if one fails (it will), or twice the opportunity to fail, open or closed. All submersible heaters appear to have one thing in common, the cheapest highest profit margin, unreliable thermostats. I started using external thermostat/controllers and cannot say enough about the difference in reliability and stability of water temperature. There is very good information at Jehmco web site that addresses these exact heater concerns. Scroll to the very bottom of the page.

Two heaters with external controller (until it fails :-), jmo. Bill

http://www.jehmco.com/html/temperature_controller.html

[RockHound]

Good info in that link, thanks Bill

[univmd]

Good evening,

It sounds like "most" everyone here recommends two heaters even for just a 55 gallon tank.

Two big heaters vs. two small heaters: very interesting point.

Is it okay to place two heaters side-by-side?

With warm regards, James

[kaceyo]

Hi James,
It's best to keep them apart frm each each other so the heat is more evenly distributed IMO.

Kacey

[Apistomaster]

I am too dense to grasp the logic of doubling the numbers of the most unreliable accessory we use in our aquariums and probably never will see the validity of the two heater concept.
The only way any heating system that uses what we have available can be made reasonably reliable is if a separate heater controller is part of the system. It really seems to me to do whatever makes the most sense to you since the end results are the same.

I have been in this hobby over four decades and have experienced my share of failures and they tend to come in two modes. By far the most common failure for me is the heater sticks in the "on" position. Second mode and trailing far behind the first, is the heater simply doesn't heat. I even have a few 100 watt heaters that are stuck at about 75*F.

On average regardless of make excluding Jaegers(I don't have enough data points) the majority of the heaters have about a 20-25% failure rate at the end of a two year period.
I have a box full of these heaters. I figure that some day I can use the majority which are the always on type can be used whenever I break down and by a heater controller that can handle a few thousand watts. I have several 250 watt bad heaters.

Everything regarding heaters and out put suitable per tank is determined by the ambient temperature and how many watts per degrees above ambient are required to maintain the set point. In theory, a reliable heater can be almost any size at or above that which is required to maintain the desired set point. I am able to use 100 watt heaters on all my tanks from the 4.5 gal Tetra breeding tanks to my 40 gallon breeder tanks and maintain 85*F. That is because the ambient room temperature is already 75*F.
I use 250 watt heaters for 55 and 75 gal tanks. That way, if I get a larger tank and keep the ambient temps the same I can use them.

This will remain an open debate until we all have degrees in mechanical engineering of HVAC systems and understand the three imutable laws of thermodynamics. Oh and one more thing, reliable heaters.

[MaryPa]

2 smaller heaters. (=POINT)

It's something I SCREAM now for years, if you don't do it and you run one day into "fish soup" I will kick your a$$ and say "TOLD YOU SO"

Hans

(Who doesn't use heaters at all because you can't trust any of them)

So how do you keep the water warm? Mine are kept at 84f. i even cover the tanks at night to be sure the temp doesn`t fall.

[kaceyo]

Hi Mary,
Hans likes to keep the room hot enough so that there is no need for heaters. If you keep the room temp in the low to mid 80"s the tanks will also be kept at those temps.

Kacey

[speakerguy]

I have historically questioned the logic of two heaters in an aquarium. The thermostat in heaters has hysteresis, so that the heater is not rapidly cycling on and off. Setting it to 82* might cause the heater to turn on at 81 and off at 83. A second heater set to 82 might actually be set to 81.5, and have a hysteresis range of 80 to 82. The accuracy of the set point, the hysteresis range, and whether or not its centered about the set point all come into play.

Theoretically, this means that one heater will be the one doing the brunt of the work to heat the tank, while the other is idle.

What would be ideal is a single large heater, with a completely separate electronic digital temperature controller that turned the heater on/off. I'm sure someone makes these, but I can't think of a mfg right now. Relying on something like bimetallic thermostats in heaters is too risky IMO and doubling up on them doesn't address the root problem - heater thermostats just suck.

Also, first post here for me - I've been a mbuna and mini-reef guy for the last several years. Pondering a venture into the discus or planted tank world with a new 50G 18x18x36 tub that I just purchased.

[jack396]

My heaters are now in a pair together, both plugged into a temperature controller. I used to shop around for dependable heater brands. Sometimes one from a company would operate very efficiently leading me to purchase others of that brand name. Alas, then one or two of them would be giving me fluctuating temperatures. Finally I invested in temperature controllers from Jhemco and my problems have ended. Yes, a bit of a financial investment at the start, but I don't even think about the heaters anymore as the controller has a large digital display in either centegrade or farenheit that is easily glanced at when near the tank. I've found them to be precise all of the time, and I have five of them on five tanks.

Seems like a lack of priorities to have many hundreds of dollars and labor on a tank full of fish all riding upon the dependability of a heater with a cheap thermostat the heater company probably paid pennies on.

[Apistomaster]

The term "hysteresis" introduced in post #19 was unfamiliar to me so I looked it up as it is used in thermal control systems. It is difficult for me to understand well because I lack any electronics background but I did discover enough to better appreciate the difficulties that are encountered in design and construction of underwater self-contained heaters present.

A quartz crystal used in the design apparently is subject to aging. That was not so difficult to grasp but that aging occurs regardless of whether the heater is on the shelf or in use surprised me. In some ways it is actually amazing that our aquarium heaters work as well as they do because of all the compromises and variables involved.

The single heater concept rather than two set close to the same range does indeed seem to reduce the wear and tear on the heater(s).

Glad this was introduced to this discussion.

[kaceyo]

The single heater concept rather than two set close to the same range does indeed seem to reduce the wear and tear on the heater(s).


While that may be true, the reason behind the double heaters is to add a safety margin so a malfuntioning heater won't fry or freeze your discus, which gets priority over heater wear and tear.
The individual heaters aren't pwerful enough to raise the temp above a safe level if it sticks "on" and you still have a working heater should one fail completely.

Kacey

[Apistomaster]

Hi Kacey,
I think the one or two heater choice is a personal preference, just like which filter systems or which type of discus are going to be kept.
Both approaches seem to have their followers and beliefs as to why they think one is enough or two heaters are better. I just happen to be comfortable using one heater.

[BAM]

I have only had discus for 4 months, in a 70 gallon tank, but I have changed my thought in those months. First, if bad stuff is going to happen, it will always happen on the one weekend of the year you are not at home. My tank is in my family room, not an extra warm (hot) fish room. I started with one 250W stealth heater and 82 -83 degree tank temperature. To hold that the heater needed to be set at 84. I fairly quickly realized I needed to be a few degrees warmer, and found the heater needed to be set at 87 or 88 to hold 84 or 85. Clearly, I was approaching the limit of its ability to heat the tank. I replaced it with two 200W stealth heaters and move the 250W to the water change tank. A single 200W can only hold about 80 degrees in my 70 gallon tank in a 68 degree room, so if one sticks on, it is not strong enough to cook the tank. If one fails completely, the tank will cool to about 80 degrees, or about 12 degrees above room temp, which is not ideal but better than a crash into the 60's if a single heater failed in January when I was away for that weekend, and more importantly, I will notice something is not right! Both would have to fail or stick at the same time to be "deadly". I reduce tha likelyhood that will happen by rotating heaters. A 200W heater can heat my 20 gallon water change tank from 55 degrees (well water) to 84 to 86 in about 8 hours. I like that because if I ever need to do alot of water changes, for example, if a fish should die when I am away for that one weekend, I would need/want to be able to change alot of water fast. The hard work I ask of my water change heater, averaging 5 changes per week, plus or minus, wears that heater out faster than the ones in the main tank. I rotate an old heater from the tank into the water change 20 gallon tank so the two heaters in the main tank do not "grow old" together. The new heater always goes into the main tank.

I know it sound complicated, but it really isn't once you determint ths size heater that is almost, but not quite big enough alone. Bad stuff always happens at the worst times. It is always good to have a plan to reduce bad chances. Good Luck!

Brad

[krazykat]

I had 2 250-watt heaters in my 90 gallon tank. One of them failed in the middle of winter and the second heater was not able to maintain tank temp at 82C, but it did keep the tank temp from crashing into the 60s. I still lost a couple of discus. I now have 2 300 watt Visi-Therm heaters in my discus tank and it seems to work out great for now. :) My tank is kept at a constant 82 degrees (I think the heaters are set to 84) and I feel confident that there won't be such a low temp drop should one fail again in the middle of winter. (Hope I won't have to find out.)

[rogge26]

I started with a 250 watt stealth heater in 50 gallon tank. It tended to get 2-4 degrees too hot.
Now I have two 150 watt ebco-jaeggers attached to a separtate heater controller based on knowledge I learned elsewhere on this forum. I have the differential set at 1 degree. My tank stays steady at 86-87 degrees. The directions on the heater controller says to set your heaters to max, but I learned elsewhere on the forum to set your individual heaters 4 degrees higher than the desired temperature. This way, if your temperature controller sticks on, you will not cook your fish. I currently have my individual heaters set at 90 degrees and my temperature controller at 87. I did not want to set my indidual heaters over 90.