is the fourth resin chamber really necessary? I run chemi pure elite mostly, but sometimes i run phosban in conjunction with seachems matrix or matrix+phosphorous absorber.... I have a fuge and plenty of live rock and sand for extra filteration. Please let me know because I am thinking of purchaseing a higher gpd unit and want to spend my limited funds wisely. I believe I am going to go with the premium reef supply brand. Thanks!