Working with the assumption that this is for your 90g tank, and that you don't have a sump set up, I'd go with an Aqua C Remora Pro with a Mag 3 pump. Stay away from the Rio pumps...they don't last. Also, I wouldn't recommend a Prizm of any type. They have a very bad habit of putting water in the floor. Seaclone makes a 150, but it's not a very efficient skimmer. You'll be fine without a skimmer for a while even after you add fish as long as you are willing to do water changes.