you could build your own refugium/sump filter under your main tank. 150 gallon is a big tank, it needs alot of filtration.
this is my marineland 120gal tank (note its too wide to go in my house right now lol)
has another tank under it, with dual filter stacks, consisting of prefilters, 3 mechanical filters (two different types of filter material, one is loose and coarse to catch big stuff and the other is much finer filters, and a 4" bed of activated carbon and bentonite for both carbon filtration and biological filtration under all the other filters. i havent run this tank yet as i cant get it in my house.... but know it is an established saltwater lobster tank, and altho it is saltwater, the theory in filtration is the same. basically your choice in filtration is up to you, your cappabilities, and most importantly your budget.