LesMelling
Registered Old Reefer
The Heater Separate Thermostat Placement Dilemma, By Les Melling.
Every so often the a question arises with regards to where a heater and the probe from a separate thermostat should be positioned. There are various plus and minuses to the various configurations you can consider to use. Here are the main ones.
1/ Heater in the sump thermostat probe in the tank.
Pros
Heater is out of view in the sump.
You will hardly notice the probe in the tank due to its small size.
Lots of water circulation around the heater, or at lest there should be.
The thermostat is reading the actual tank temperature and not the sump temperature and so is controlling the tank temperature not the sumps temperature.
Cons.
If your sump return pump fails, the thermostat reading the actual tank temperature could easily keep the heater turned on causing the sump to overheat and wiping the bacteria in the sump along with any other life forms you have in it including any algae you might have growing in there.
If the probe should come out of the tank accidentally, then the tank and sump could overheat with disastrous results.
You need a good turnover of tank water through the sump to ensure correct temperature but you should have that anyway.
2/ Heater in the Tank Probe in the Sump
Pros
Heat directly in the tank itself
Cons.
If sump return pump fails the heater could stay turned on overheating the tank.
This is by far the least recommended configuration IMO.
You need a good turnover of water through the sump as always.
3/ Heater in the sump thermostat probe in the sump.
Pros
The thermostat controls the heater as the water from the tank flows through the sump before returning to the tank. Note. Place the probe near the inlet to the sump with the heater near to the return pump.
No equipment in the display tank.
This might just be the best configuration especially if you want minimal equipment in your tank and is one of the safest ways for your aquarium heating set up. .
Cons
If return pump fails there will be no heated water returning to your tank for a period of time until you carry out remedial action.
4/ Heater in the Tank Thermostat Probe in the Tank.
Pros.
Probably the safest configuration.
Heater and thermostat in unison both working with the tank temperature. If using this configuration the probe is best placed some distance away from the heater. .
Cons.
You may not want to see the heater in the tank and it might not be possible to hide it from view along with the cables to each.
Other things to consider.
Many people prefer to use a heater thermostat (all in one) along with a separate external thermostat, this will give you double security. If employing this method then the heater thermostat should be set 1 degree higher than the external thermostat. This way, if the heater should fail by sticking in the on position the external thermostat will prevent the heater over heating as it will only allow the heater to rise to the set temperature.
If the external thermostat fails and sticks on the heaters own thermostat will kick in and only allow the heating element to rise one degree over what you have set the external thermostat to.
The only downside to the above is that you now have two thermostats which could fail either stuck on or off but in essence is a more reliable set up.
Another way people often prefer to set their heating up is with 2 heaters or heater thermostats splitting the required wattage in half. In other words, if your tank requires around 400w of heating you would split that requirement into 2 x 200w heaters/heater thermostats. The advantage of this is should one fail the other would help keep the tank heating going until you got another. If one stuck on then it would take a lot longer for the tank to overheat, also with 2 heaters you have some backup in the event of one failing and providing no heat.
Titanium heaters v glass heaters
Unfortunately some titanium heaters have an iron screw under the rubber cap and have been known to rust causing major problems in the display tank. One such report is of Aqua Medic titanium heaters having this rusting screw problem. If you have one such heater I would advise pushing back the rubber cap exposing the screw to check it. I have been told this screw can be removed and the hole plugged with silicone. I do not take any responsibility for any modification of manufacturers equipment you may attempt including this mod however.
Another thing about heaters that don't have a thermostat is that should the external thermostat fail in the on position there is no back up to turn the heater off and it will continue to supply heat to the aquarium with dire consequences.
Glass heaters are a lot more fragile and have been known to break for a variety of reasons notably by either overheating or occidentally damaged, Glass heaters have even been known to have been attacked and broken by some large fish. The dangers of which to your tank and you are obvious,electricity and water do not mix especially salt water which is more conductive to electricity than fresh water. It may not be obvious that there is a crack in the glass body of the heater as it can be hard to see sometimes.
A word on external thermostat probes. ALWAYS secure the probe to the aquarium or sump in some way, I use an old airline clamp that fixes on the edge of the tank or sump and is secured by gripping screws which grip the edge of the tank or sump glass. The clamp also has a securing screw to secure the cable of the thermostat probe to it original used to secure airline.
Every so often the a question arises with regards to where a heater and the probe from a separate thermostat should be positioned. There are various plus and minuses to the various configurations you can consider to use. Here are the main ones.
1/ Heater in the sump thermostat probe in the tank.
Pros
Heater is out of view in the sump.
You will hardly notice the probe in the tank due to its small size.
Lots of water circulation around the heater, or at lest there should be.
The thermostat is reading the actual tank temperature and not the sump temperature and so is controlling the tank temperature not the sumps temperature.
Cons.
If your sump return pump fails, the thermostat reading the actual tank temperature could easily keep the heater turned on causing the sump to overheat and wiping the bacteria in the sump along with any other life forms you have in it including any algae you might have growing in there.
If the probe should come out of the tank accidentally, then the tank and sump could overheat with disastrous results.
You need a good turnover of tank water through the sump to ensure correct temperature but you should have that anyway.
2/ Heater in the Tank Probe in the Sump
Pros
Heat directly in the tank itself
Cons.
If sump return pump fails the heater could stay turned on overheating the tank.
This is by far the least recommended configuration IMO.
You need a good turnover of water through the sump as always.
3/ Heater in the sump thermostat probe in the sump.
Pros
The thermostat controls the heater as the water from the tank flows through the sump before returning to the tank. Note. Place the probe near the inlet to the sump with the heater near to the return pump.
No equipment in the display tank.
This might just be the best configuration especially if you want minimal equipment in your tank and is one of the safest ways for your aquarium heating set up. .
Cons
If return pump fails there will be no heated water returning to your tank for a period of time until you carry out remedial action.
4/ Heater in the Tank Thermostat Probe in the Tank.
Pros.
Probably the safest configuration.
Heater and thermostat in unison both working with the tank temperature. If using this configuration the probe is best placed some distance away from the heater. .
Cons.
You may not want to see the heater in the tank and it might not be possible to hide it from view along with the cables to each.
Other things to consider.
Many people prefer to use a heater thermostat (all in one) along with a separate external thermostat, this will give you double security. If employing this method then the heater thermostat should be set 1 degree higher than the external thermostat. This way, if the heater should fail by sticking in the on position the external thermostat will prevent the heater over heating as it will only allow the heater to rise to the set temperature.
If the external thermostat fails and sticks on the heaters own thermostat will kick in and only allow the heating element to rise one degree over what you have set the external thermostat to.
The only downside to the above is that you now have two thermostats which could fail either stuck on or off but in essence is a more reliable set up.
Another way people often prefer to set their heating up is with 2 heaters or heater thermostats splitting the required wattage in half. In other words, if your tank requires around 400w of heating you would split that requirement into 2 x 200w heaters/heater thermostats. The advantage of this is should one fail the other would help keep the tank heating going until you got another. If one stuck on then it would take a lot longer for the tank to overheat, also with 2 heaters you have some backup in the event of one failing and providing no heat.
Titanium heaters v glass heaters
Unfortunately some titanium heaters have an iron screw under the rubber cap and have been known to rust causing major problems in the display tank. One such report is of Aqua Medic titanium heaters having this rusting screw problem. If you have one such heater I would advise pushing back the rubber cap exposing the screw to check it. I have been told this screw can be removed and the hole plugged with silicone. I do not take any responsibility for any modification of manufacturers equipment you may attempt including this mod however.
Another thing about heaters that don't have a thermostat is that should the external thermostat fail in the on position there is no back up to turn the heater off and it will continue to supply heat to the aquarium with dire consequences.
Glass heaters are a lot more fragile and have been known to break for a variety of reasons notably by either overheating or occidentally damaged, Glass heaters have even been known to have been attacked and broken by some large fish. The dangers of which to your tank and you are obvious,electricity and water do not mix especially salt water which is more conductive to electricity than fresh water. It may not be obvious that there is a crack in the glass body of the heater as it can be hard to see sometimes.
A word on external thermostat probes. ALWAYS secure the probe to the aquarium or sump in some way, I use an old airline clamp that fixes on the edge of the tank or sump and is secured by gripping screws which grip the edge of the tank or sump glass. The clamp also has a securing screw to secure the cable of the thermostat probe to it original used to secure airline.
