I have 3 150W EJ heaters in the sump of a slightly smaller tank than yours. Heater1 and Heater2 take turns with primary duty, assisting each other if heating takes too long. The third heater is a backup in case either of the other two fail. With the code below, the water temp both in the overflow before the heaters and in the sump return compartment after the heaters is maintained within a range of 0.6 F at all times and within a range of 0.3 F more than 90% of the time. This degree of temperature control may not be necessary, but I prefer it. Note that this does result in increased EB832 power relay on/on cycles per day (~20) for each heater. It's much the same as with home heating - If you want tighter control, set your equipment to cycle more often and understand that it may wear out faster.
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[Heater1]
Fallback ON
If Temp < RT+0.0 Then ON
Defer 001:15 Then ON
If Temp > RT+0.1 Then OFF
If Time 16:00 to 03:59 Then OFF
If Temp < RT+-0.1 Then ON
If Output Heater2On030 = ON Then ON
If Output HeatersOn045 = ON Then OFF
If Temp > 78.7 Then OFF
[Heater2]
Fallback ON
If Temp < RT+0.0 Then ON
Defer 001:20 Then ON
If Temp > RT+0.1 Then OFF
If Time 04:00 to 15:59 Then OFF
If Temp < RT+-0.1 Then ON
If Output Heater1On030 = ON Then ON
If Output HeatersOn045 = ON Then OFF
If Temp > 78.7 Then OFF
[BackupHeater]
Fallback OFF
Set OFF
If Temp < RT+-0.2 Then ON
Defer 000:30 Then ON
[Heater1On030]
Set OFF
If Output Heater1 = ON Then ON
Defer 030:00 Then ON
[Heater2On030]
Set OFF
If Output Heater2 = ON Then ON
Defer 030:00 Then ON
[HeatersOn045]
Set OFF
If Output Heater1 = ON Then ON
If Output Heater2 = OFF Then OFF
Defer 045:00 Then ON
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