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Thread: Mutiple Heaters
02-13-2012, 01:30 PM #1
On my 45, I have two heaters for redundancy purposes and I'm planning on dong the same for my 55. So instead of doing one 200 watt, I'm plan on getting two 150 watt heaters. Thoughts?
Also, how many of you do the same thing?55g: Planted Tank: Firemouth, Blue Acara, Rainbow Cichlid, 15 Bloodfin Tetras, and 8 Panda Cories
45g Planted Tank: 2 Koi Angelfish, 19 Rummy Nose Tetras, and 6 Green Cories
20g Planted Tank: 8 Harlequin Rasboras, 4 Peppered Cories, and 8 Amano Shrimp
02-13-2012, 01:40 PM #2
I see no reason to waste money on under-wattage heaters. It costs about a dollar more to get the wattage that works for your tank. I would get one. It's always nice to have a back up tho but a good heater should last at least a few years.
02-13-2012, 01:43 PM #3
I use two on larger tanks but IMO you should not reduce the wattage of the ones you use. This will just make at least one of them work harder and not last as long. As an example, I have two 300 watt heaters on my 90g. You can rarely get both heaters to be exactly in sync, so only one is usually on.
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02-13-2012, 01:47 PM #4
+1 to above. A second heater is a back up in case the first one fails, so it shouldn't hardly come on. If the first one fails, then IT has to carry the main load. So both heaters should be able to heat the tank on their own.20gal long planted community
02-13-2012, 02:05 PM #5
You don't want to oversize heaters though, because heaters can fail and shut off but they can also fail and lock on. If that happens and the heater is powerful enough, it'll cook the tank.300 gallon mega tank: build in progress
75 gallon community tank: tetras, danios, corys, platies, otos, pearl gouramis, bristlenose pleco, assassin snails, red cherry shrimp, bamboo shrimp
70 gallon growout tank: clown loaches, sailfin pleco
60 gallon goldfish tank: fancy goldfish
29 gallon frog tank: 1 bullfrog
10 gallon and 5.5 gallon betta tanks: 1 male betta each, sometimes snails
02-13-2012, 03:40 PM #6
i use two smaller watt ones that way if one sticks on it doesn't cook your fish
02-13-2012, 07:05 PM #7
02-14-2012, 03:29 AM #8
I use 2 for even heat distribution. Using 1 is also fine. I've had a heater lock on before, luckily no fish died but the temp was in the 80's.
02-25-2012, 08:24 PM #9Member Platy
- Join Date
- Jun 2010
0Originally Posted by Gumshoe218
As long as all heaters are working, the specific wattage does not matter at all, as long as the combined wattage is sufficient. (You can even use a wild mix of completely different wattages.) Two 150 watt heaters will do exactly the same amount of work as one 300 watt heater, assuming their negative feedback loops are working well (i.e. they don't "stick" in on or off position).
Of course, if one heater fails, you'll end up with only one 150 watt heater. How well it will perform its duties will depend on how much wattage you really need in your tank. If you really need a redundant system that can sustain itself for long time even after one failure, better opt for two heaters, each with adequate wattage to maintain the tank alone.
02-25-2012, 09:14 PM #10Member Oscar
- Join Date
- Nov 2008
If you go with 2 heaters, keep in mind that its almost impossible to set them both to exactly the same temperature. Thus, one will always turn on before the other.
If both heaters are of adequate size for the tank, then the heater that turns on first will be the primary heater for the tank. The secondary heater will never turn on and will be used only in event of a failure of the primary heater. The primary heater will do all the work.
If both heaters are of insufficient wattage to maintain the set temperature, then one of the heaters will turn on and the temperature will continue to drop until the the secondary heater turns on. Depending on how far apart the heaters are set, the primary heater will remain on all the time with the secondary heater switching on and off to maintain the temperature. If they're set close enough, and their thermostat hystersis' are close, then you might see some sharing of the load, but this is unlikely.
In the first situation, redundancy only happens if the primary heater fails open. If it fails closed, the tank overheats. In the second situation, there is no redundancy at all because if either heater fails, the temperature cant be maintained.
There may be reasons to use two heaters, such as for distribution of heat, but redundancy isnt a good reason. You'd be better off with an over/under threshold alarming thermometer to let you know if the heater fails.