Need some suggestions as to what heaters are worthwhile. I have a 155g with a wet/dry. I'm thinking that 2 heaters would be best so as to have a backup in the event of a failure. Will probably use some type of controller. Do you think 2- 300w heaters would be best and what brands and types are being used. If I did use 2 heaters and one failed is there some type of indication maybe via the controller that would alert me to the fact that one failed?