Heater Question

[Reef23]

Hello,
I had 2 100W Marineland stealth heaters that were recalled. They sent me a 300W heater to replace the 2 x 100W. Now the 300W heater is shot and not working after only a few weeks. Im in the process of upgrading systems and they sent me a refund. What is the best heater options for a 140G+40G sump. I have always heard that running multiple heaters is the best in case the thermostat goes on one. Any suggestiosn ? Whats everyone else running?
Thanks