I have had freshwater fish my entire life and really want to switch to a saltwater tank. I was recommended by a friend to get a nano cube because it is one of the best. I was wondering if you guys had some suggestions. I am not looking for a big 50 gallon tank but i would like something aroudn 20-30 gallons are the nano cubes the best for beginners and what are the chances the built in pumps go and I loose all my marine life? What backup pump would you recommend me get in case that happens?