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Thread: 1 or 2 Heater
11-20-2012, 03:26 AM #11Member Oscar
- Join Date
- Nov 2008
just keep in mind that its impossible to set the thermostats of the heaters to exactly identical temperatures. One of the heaters will always be doing all the work.
So keeping that in mind there are two scenarios
1. Both heaters are large enough to maintain the temperature by themselves:
In this case, one heater will be doing all the work. The other will be idle.
2. Both heaters are too small to maintain the termperature by themselves:
In this case, one heater should be always on, the other will cycle to maintain the temperature.
The typical failure mode is where the thermostat welds itself on. None of these two scenarios offer any protection against that. In case 1, if either thermostat fails, the tank overheats. In case 2, if the always on heater fails, there's no affect. If the cycling heater fails, the tank still overheats.
So it's the situation of "the more complex the sysem, the more likely it is to fail". Two heaters are twice as likely to fail as one heater because there are twice as many parts and offers no redundancy.
11-20-2012, 01:15 PM #12
This is one area that baffles me - no piece of aquarium equipment is more important than a heater; even filters are not since water changes can handle that issue (and yes, a lot of work but many discus keepers do exactly that! Every single day 100% water change.) But without a heater tropical fish can not be kept at all.
Two heaters are nice since this tends to provide better water temp across the tank and does give redundancy for this absolutely essential piece of equipment. If failure is an issue (my heaters only fail in the off mode - nice design there) they do sell devices that can sense this and turn the device off - I have one but put it away after I discovered that my heaters have a fail-safe design mode.
I do have my heaters set so they both operate at the same time (within a minute of each other) - this is possible for larger tanks that are well stired and one also has submeraged heaters installed. I agree that this is very difficult to do for smaller tanks. And yes, two heaters are twice as likely to fail. That is why I like fail safe units.
A submersible heater is the best device as far as heaters are concerned - far more uniform tank water column and the least likely to be exposed to air if you lower the water level for cleaning. Most such heaters tend to be metal and are nearly indestructible.
Last edited by Cermet; 11-20-2012 at 01:22 PM.
11-20-2012, 02:01 PM #13
The one i have (Fluval M300) says submersible, but also has the water line you are not supposed to go over, I just have it dead center of the tank vertically and it goes on every few mins, off for a few mins and so on.
My wonderful gf reminded me that I also have the heater that came with the tank (not sure on wattage as it is old as hell) but it does work so I do have that as a backup in case my fluval goes down.
11-20-2012, 09:57 PM #14
If the heater is comming on every few minutes, either you just started it (I assume) or the room is very cold.
A submersible heater means the the entire assembly works under water. These are made to do that and are mostly, but not always, made of metal.