DOC verses Nutrients

[wattson]

We are always seeing threads where peoples corals are doing subpar or starving,,as normal it is suggested to add more nutrients (No3 and Po4)either dosing the compounds or try to feed the corals,fish and all life into the aquarium to raise No3/Po4 ..
Which part of DOCs is beneficial verses needed to be skimmed or water changed out for better health of the corals and reef water quality?
Also,,NO4 and PO4 are considered to be nutrients,,whats the difference between these two verses DOCs ?
What is the main contributor of "Yellow Water " in our aquariums in which GAC is used to minimize or eliminate ?

 

[Randy Holmes-Farley Verified Community Expert]

Yellow water is caused by organics in the water that have a structure capable of absorbing blue light.

I'm not sure what you mean by "which part" of DOC's.

There are more different DOC's in the ocean than fish.
Most are capable of being metabolized by at lease some organisms, especially bacteria.
Some are toxins.
Some absorb light.

Organic carbon is considered a nutrient for a heterotrophic (nonphotosynthesizing) organism such as many bacteria. But random organics wouldn't normally be considered a nutrient for many photosynthesizing organisms (such as green hair algae) that neither need nor can metabolize many of them.

Most required trace metals such as copper will also be bound to organic matter in the ocean.

I discuss organics here:

Organic Compounds in the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2004-10/rhf/index.htm