The amount of bio-media needed, is based on available food, in the form of ammonia, nitrite, and nitrate, and other waste products produced by metabolism, ....... not on the amount of phyisical bio- media crammed into any type filter
In my sump, I have 3 six inch bags of media, and a 20" x20" square of porrett foam that filter my overcrowded cichlid tank.
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You can have a 6 ft sump filled with bio-media, and it won't do any more than those 3 bags of media, once collonized by beneficial bacteria.
Of course, it is possible to have too little, but if your testing results at 0 ammonia. 0 nitrie, and almost undetectable nitrate, you are golden.
Just like the tests below
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And the testing I do where I collect fish in nature.
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