Well, I think that using a controller, like Apex or any other, is a great head start, but it's not all. There are many ways of adding redundance to a system, like putting check valves and other "plumbing devices" on the right place. Also putting the sensors and float switches in the right place, so none of them have a chance to work improperly. And even if they do work improperly, or if the plumb breaks, or if the main pump stops, or if you run out of water and electricity in your house for a week, or if your sump explodes, or any other problem occurs, it's always important (vital) to have backups to the backup backing up the backups, so your aquarium don't ever crash, and have it's "passangers" killed. You have to be prepared to the expected and to the unexpected too. And the best (only) way to assure all this safety is to build a project for your tank, and not just watch a few videos and read a few articles about saltwater tanks and go out thinking you already knows everything there is to know about the hobby and that you are ready to build the best tank ever seen. I think that the more you learn about this hobby, the more you find out you don't know anything realy. And the best you can do when building your project is try to anticipate some of the things that may happen when the tank is running, and try to be as prepared as you can to the things you don't know that can happend. Indeed, I've made one of my favourite hobbys trying to invent new ways to destroy my tank. And every time I had a new idea of how to destroy it, I had a new idea of how to save it from been destroyed when actually running. Of course that, probably, almost everyone reading this already knows everything I said, but it is easier said then done, especially when it comes to having to wait to buy that bigger tank that I've always wanted, which makes people don't spent as much time as they should building the project of the tank, and just going to the nearest LFS and buying everything they can with the money that they have in that moment. In my opinion, that is one of the biggest mistakes one can make when building a saltwater tank, or any tank at all. In fact, all this fits into many activities that requires planning, and when one skipps that part, he is doomed to "crashing".
Sorry for the bad english,
Rafael Zambon
