What an interesting question, John. Thank you for asking. I'm afraid I cant answer it definitively but will lend my thoughts and maybe that will spark a dialog with more knowledgeable members. My take is this...
When I set up my first true reef aquarium (1987) a mentor, whose name has long been forgotten, instructed me to do the
LR,
DSB, and LS thing. Then let it operate through the cycle without adding anything. He further instructed me to NOT add any fish to the system but, instead to add a typical "clean up crew". Check for a mini cycle for a few days and when things settled again, add some CORALS but, no fish. Having graduated from fish only aquariums, I was anxious to add fish. He explained, fish are the BIGGEST POLLUTERS in our aquarium while corals ADD LITTLE in the way of pollution. My friend explained further, if you add fish you will have algae problems beyond your imagination because, your bio load will quickly overload your systems ability to handle the waste produced by the fish. I do my best to continue that practice today. I really think the truly beautiful reefs you see today, that are thriving with a huge bio load consisting of a diverse mixture of corals, fish and invertebrates, were set up this way.
So, my take on coral as a bio load is that they add some to the total but much less that other things such as fish. Corals derive much of their energy from their symbiotic algae living within their tissue. The coral utilizes sugars produced by the algae and the algae utilizes the waste of the coral as it's source of energy. Consequently, little "bio load" is placed on the system.
As far as Corals removing
Nitrates, i haven't heard that. I have heard the Clams utilize
Nitrate in their metabolism.
This is what I recall. Hopefully others will chime in here.
Dick
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