BigJim
Aquarium Advice Addict
Short answer: Yes, heater wattage is cumulative. Long answer: It's long and complicated and really unnecessary in this case.
Two heaters are generally preferred to one large heater. There's less chance of a tank catastrophe if a heater dies or runs away. The other heater will compensate if one dies and a smaller heater can't heat the water as quickly in the case of a runaway.
Two heaters are generally preferred to one large heater. There's less chance of a tank catastrophe if a heater dies or runs away. The other heater will compensate if one dies and a smaller heater can't heat the water as quickly in the case of a runaway.