There are countless ways to filter a fish only system...on my 58 fish only I use a combination of 50-60 lbs of LR...a well established DSB of about 5"-6"...a CPR BacPac2r skimmer(hang on type)...and a single hang on mechanical(that primarily provides additional circulation...but I do run carbon/phosphates sponge in it now and then).
This basic filtration system mainatins my fish only tank well enough to maintain decent water chemistry but it could be seriously improved on. The only problem I've had with it in over two years is a steady nitrate reading of 60-80 ppm.
Like I said there are numerous ways to set up the filtration for your system...it really depends on what you plan to keep and the bio-load pressure on your system.
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