you don't want the bio ball set up. it's going to eventually work against you. as i said, you can make a sump out of a 20 long or something similar if money is an issue. i can walk you through that if necessary.
to answer your question, no, you don't really need a refugium, but it's a great benefit to have one. it is an excellent way to lower the nutrient level in the system, and also to grow pods
. it's yet another component to keep your tank healthy. btw, that was a sump i linked you to, it just has been partitioned to include a refugium. a sump is just an extra tank that shares the same water.
you could also check your local craigslist and backpage for deals. many folks sell used equipment there. (it's mostly people who try to cut corners and fail miserably, then give up).
if you want clams, anemones, and stony corals you will need powerful lighting. you have a few choices with lighting. you can go with metal halides (i would recommend 2 x 250 watts), high output T5 (i would want 6x54 watt), or LED
, which is the most expensive. all of these have their pros and cons, but all of them will allow you to keep whatever you want, providing you buy a quality unit.
one more thing- is there any way at all you can return the 55 and purchase a 75 maybe? the 55 is going to be quite challenging to aquascape and is going to limit you on a few fronts. while you are at it, you can get a reef ready tank and skip the HOB
overflow box. it will make your life a lot easier.
if you stay in this hobby and have success, you will thank me later for this suggestion.