A secondary controller like Inkbird is a good idea BUT don't count on that alone. I had an Inkbird screw up and devastate a tank. Try using two heaters, both small enough so if one goes full throttle it won't be able to get too hot.
I bought three at RAP and they all seem to be doing great. Yes, at the show the water was murky but that is exactly what sold me on trying them. I figured if they still looked good in that soup I should have no problems. The Alk, Calcium and Magnesium are good but the Nitrates and Phosphates are...