what are the pros and cons of using two smaller pumps instead of one large one for a two return system? I am leaning towards two in case one fails but since I am going to be using a laguna is that a real risk I need to consider?
I like 2 pumps, even if one is very large and the other small. Having one go out is only an issue if its the only one you have. An unattended tank even with ~25-33% of required flow will keep the tank going long enough to deal with the situation.