Monday, March 5, 2007

Heater Failure Experiment On A 10G Aquarium

Following is a thread I started on a forum, which led to my conducting this experiment, which was chronicled back on 11/29/2006 thru 12/01/2006.

I was reading about this on another forum and thought it would be a good thing to talk about here. I am also conducting an experiment on a 10G tank below to see just how fast it will cool down and heat up with a malfunctioning heater or lack of one.

Steve S., who is a very knowledgeable fish keeper and posts often in another forum said this (to someone who had a failing heater):

"... The idea of having two heaters of lesser wattage is to prevent against your current problem. Heaters do fail. It is just a matter of time. If they fail as yours has, then the one would be left to help maintain the water temperature while you go out and get another one. Should the heater fail in a way that would cause it to always be on, then it would not leave you with an overheated tank.

\\ Steve //

This is one of those things that made me go "DUH!!!", so simple, but most of us don't think about the simple things like this. Besides being safer for your fish, smaller 25W or 50W heaters can usually be purchased much cheaper than larger ones. I believe the "rule" is 5W per gallon so this dual-heater system would probably work better with larger tanks. Smaller tanks don't have as much room to hide equipment but they are more susceptible to rapid temperature changes... but it's those bigger tanks that cost so much more money for things and fish if they go wrong. The smaller heaters are easier to hide behind plants or decorations too.


MjRyan - Thats how i do it, ever since i had one overheat and raise the temp to 102*. woke of and my colombian's where floating at the top. Now i will only do a 2 heater setup.

Moneygetter1 - AGREED!! I also use two heaters of lesser wattage. It serves 2 purposes-
1} Distributes the heating of the water more evenly (when placed on opposite sides or upper & lower areas along back of the tank.
2} Redundancy acts as safeguard in the event of unit failure & gives you a little more time for corrective action.

Essabee - I always do multiple heaters for the quoted reasons and always advice it to everyone.

Albacore - For a larger tank, about 55 gal, I go for two heaters, to get even distrib. but for smaller tanks it not really important. I once after a PWC, I left the heater unplugged on my tank, FOR A DAY AND 1/2. I noticed it when my temp went down 2 deg. it takes a long time for heat to leave water. Yes it not good but if your heater stopped working you have a good day+ on most small tanks to get a new heater for them before temp changes like .5 deg. BUT it might just be where i live and the conditions around when it happened. temp in tank normal 79, temp in home 67-69. but yes it makes a good back up and would recommend one on anything about 55 gal and up. Just what i think.

GoldLenny - If your temp only went down 2F in a day and a half, then your room temp was only 2F lower than your tank temp. I promise you a 10G tank will assume room temperature within several hours of losing the heater. I have an empty 10G on my kitchen counter so I'll do the science right now and post my results in this thread.

11/29/2006 - ~4:00 p.m. - GoldLenny - I just filled the 10G with cold tap water at 64F. Room Temperature in my kitchen is 75F. It's 3:55pm CST. I'll report back in an hour or two. When it assumes room temperature, then I'll put in a heater, raise it to 80F and see how fast it cools down back to room temp also. This will also show what happens when it gets warm during the day and cooler at night in a home... usually.... to show what happens to a 10G temperature range without a heater. I know physics dictates that a 55G would take a lot longer to change temperature up or down but someone with an empty 55G would have to do that test.

11/29/2006 - ~5:00 p.m. - GoldLenny - I took a temperature reading after one hour and it had already started to rise a little. One thing I thought of is that I do not have a filter running on this tank which will make the temp change more slowly then on a tank with water agitation so this experiment will actually show that an actual tank will change temperature even more quickly due to the water agitation and the constant change of water on the glass surfaces and top surface area that are exposed to the different room temperature. It's kind of how a convection oven cooks a lot faster than a regular oven because of the circulating air keeping constantly HOT air on the surface of the food instead of a slight buffer zone with a slightly lower temperature. My two hour temperature readings will be posted shortly.

11/29/2006 - ~6:00 p.m. - GoldLenny - OK. It's 5:55pm CST, two hours later and the tank has risen from 64F to 66F, two degrees Fahrenheit. From what I remember in science class a long time ago, water will cool faster than it will warm given identical applied temperature variations so if it is warming up by 1F per hour, it would cool down even faster, in the event of a failed heater stuck in the off position.

The reason water cools down faster is because of evaporation when the water is warmer than the air surroundings. When water is warmer than the ambient air, water releases the heat via evaporation. This results in steam or fog when the difference is very large but there is still evaporation even when the difference is very little, which is why you get condensation on the cover glass of your tanks. Ambient air does not "evaporate" into the water, it just slowly changes raises the temperature.

Whew. I can't believe I still remember some of these physics, chemistry and earth science basics.


MjRyan - (quoting)"goldlenny (11/29/2006) If your temp only went down 2F in a day and a half, then your room temp was only 2F lower than your tank temp. I promise you a 10G tank will assume room temperature within a couple of hours of losing the heater. I have an empty 10G on my kitchen counter so I'll do the science right now and post my results in this thread."

In the sense you talk about, your right, it isn't really important... I am NOT worried about the temp dropping. but wait until one of your heaters mal's and stays on overnight while your sleeping. Your fish will be at the top floating from the hot tub they didn't enjoy. Using a 1/2 rec. watt heater and that problem is eliminated as it wont have enough power to heat the whole tank.

Good Test Lenny

Back to GoldLenny posts:

11/29/2006 - ~11:00 p.m. - GoldLenny - I had to run out for a few hours but I just checked the temperature at 10:55 p.m., seven hours since setting this experiment up and the temperature was up to 70F, a full SIX degrees Fahrenheit rise in seven hours. The 1F per hour rise is slowing down, as I suspected it would, as it approaches temperature equalization. I'm heading to sleep in a little while so I'll check it again in the morning.

11/30/2006 - ~7:00 a.m. - GoldLenny - Some time in the middle of the night, the tank assumed room temperature of 72F since that is what both were when I woke up this morning. I forgot to post it here first thing though. I'm now putting a 50W heater in the 10G test tank and I'll see how long it takes to raise to 80F.

EDIT - I forgot I had a 10G HOB filter not being used so I just added it to the test tank too so now I'll be able to get more accurate test results on how long to heat up and cool down with a broken heater. As of 10:30 a.m. CST, the tank was 72F still (since I just put the heater in it) and I have the heater turned all the way up to the highest temperature to see how hot it will get and how fast.

11/30/2006 - 11:00 a.m. - GoldLenny - At 11:00 a.m. CST, just 1/2 hour after putting the 50W heater in the 10G tank, the temp has risen from 72F to 74F. That would be considered a huge jump if the tank had fish in it. This just gives you an idea of how fast a heater will heat up a tank. I knew once I added the filter system, things become far more dynamic over a stagnant tank. I'll report back again later in about 2 hours. Wish I would have done this on a weekend where I could monitor things hourly but it still shows just how fast a 10G tank can change temps when a heater fails.

11/30/2006 - 12:00 Noon - GoldLenny - At 12:00 noon CST, just 1.5 hours after putting the heater in the test 10G tank, the temp is up to 77F, 5 degrees F in just 1.5 hours. And the heater is still on so I'll see just how hot it will make the water before it peaks out, then I'll let it cool down again to see how fast it cools down with the filter system now running on the tank.

11/30/2006 - 4:00 p.m. - GoldLenny - 4:00 p.m. CST, it's up to 82F. That's a 10F increase in 5.5 hours with the heater "stuck" on the ON position (since I have the thermostat all the way up). I'm not sure how much higher it will go but I'll check in again in a couple of hours and then turn the heater off to see how fast it cools back down to room temp.

11/30/2006 - 7:00 p.m. - GoldLenny - At 7:00 p.m., the temp was up to 84F and that is probably as high as it will get since I think that is what the 50W heater will do to a 10G tank, if I'm not mistaken. I'm going to wait until 8 p.m. to see if it goes up any higher and then turn off the heater to see how fast it cools off.

The key here is that a malfunctioning heater or thermostat stuck in the ON position will heat up your tank from 72F to 84F, 12 degrees F, in just 8 hours. That's probably enough to seriously stress out most fish.

11/30/2006 - 8:00 p.m. - GoldLenny - 8:00 p.m. - The temp was still at 84F, which I think is the max temp from this 50W heater in a 10G tank, so I unplugged the heater. I'll check temp every hour till I go to sleep tonight.


11/30/2006 - 10:00 p.m. - GoldLenny - 10:00 p.m. CST - Temp is down to 82F, so it's dropping at 1F per hour in the first two hours.

11/30/2006 - Midnight - GoldLenny - Midnight CST - Temp is down to 80F so it has been steadily dropping 1F per hour with the heater off.

This means if you have a heater failure and it got stuck in the ON position, your tank would get very warm, very fast at 1.5F per hour. If the heater failed in the OFF position, your tank would cool down at the rate of 1F per hour.

Either of these scenarios would be very stressful, if not catastrophic to a 10G tank. I guess I'll be looking at getting a couple of 25W heaters in the near future for my 10G tank.

The larger the tank, the less volatile the temperature variation (at least according to basic laws of physics) but the value of stock in a larger tank is a lot more money so it is even more important to keep them stable as well.

12/01/2006 - 8:00 a.m. - GoldLenny - 12 hours after turning off the heater -
Temp was down to 72F, 14F degrees lower than it was when the heater was turned up all the way, in just 12 hours.

CONCLUSION - A malfunctioning 50W heater on a 10G tank could be catastrophic whether it fails in the ON or OFF position. Either event leaves your tank rapidly changing the temperature by 1F or more per hour, until it reaches room temperature or the maximum temperature that the heater can attain, either of which are very stressful to most fish. This type of event could lead to an Ick outbreak, a faltering immune system (causing many other health issues) and/or DEATH.

Thanks for reading.

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