OK guys, some safety tips:
a) Design it to fail: In other words think of Murphy, if it can fail it will and will do it at worst time, probably 5 minutes after you had closed the garage door in the way to the airport for a two day business trip.
What does this means... Heaters can fail several ways and here are the key ones:
1. Fail to turn OFF. A temperature controller in series to the heater thermostat can provide a fail safe, set the heater thermostat say to maintain 80*F and the controller to shut off heaters at 78*F, If the controller fails to shut it off the thermostat will try to keep no more than 80*F
Using two heaters might also help if one gets stuck on might not have enough power to heat the whole tank very fast. If you have a chiller the chiller might be able to counteract the effect of a smaller heater stuck on but not a single large one.
2. Fail to turn ON: Here the use of two heaters is also advisable. In this case if the controller fails to turn ON there is no much to do unless you also use a second controller, if the controller turns ON but the heater thermostat do not, having two smaller heater might one turn on even if the other does not.
By the way I have noticed that most of the time fail to turn on is not a really big problem as pumps and lighting may provide enough heating to keep things going for long while.
3. It will short circuit hot to neutral: this might be a big deal as the GFCI will not trip but the wires will overheat and you are at the mercy of your breaker, insure your supply wire is not overloaded and the breaker is sized right for the wire gauge.
4. It will short circuit hot to tank water: Unfortunately this is one of the most common and at the same time the most dangerous.
If your tank is not grounded (not ground probe) the short circuit will be there but nothing will show until you put your hand in the water, if you have a GFCI you are lucky and it will trip saving you from a good shock, if you do not have a GFCI and unlucky enough to become a good conductor to ground... well see you in haven or a similar place.
If your tank is grounded and you have a GFCI then the GFCI will trip as soon as the short circuit is established.
If your tank is grounded and you do not have a GFCI then you can say "by by critters" as the breaker does not act fast enough to prevent the corals and fish from dying and some times not even fast enough to prevent a fire specially is the short circuit is not absolute.
So for this case ALWAYS use a GFCI and insure it is in working condition, the use of a ground probe after the GFCI is optional.
5. Make it accessible: If it takes three hours and several plumbers to take the heater out for regular cleaning and wiring inspection they will not be maintained. Sure you might have found out by now that calcium and alkalinity are not the only things that need maintenance in your system. Heaters tend to get encrusted with carbonate precipitation and salt water is harsh on rubber seals and wire insulation making it hard and brittle making the insulation develop crack when flexed. The moment you notice the wires or rubber seals have lost flexibility replace the heaters.
Be Safe and Enjoy!
PS, Hans. I know you can be a multitasker but have you hear about multitesters? :lol:
