ca/alk unbalancing again?

[charles matthews]

Randy,

Regarding sources of unbalancing ca/alk, aren't there other processes besides water changes that directly export nitrate? Polyfilters do, of course; carbon does; what about a skimmer? What about nonphotosynthetic organism uptake, such as by sponges and clams?

:confused:

[Randy Holmes-Farley]

I assume that you are referring to my recent article?

I do not believe that polyfilters or carbon or skimmers remove much nitrate as nitrate ion. They remove organics mostly (despite some claims otherwise), and when removed as organics, they do not impact alkalinity.

Any nitrate taken up into an organism will be made into organics primarily, and thus will not impact alkalinity. This includes uptake by corals, coralline algae, macroalgae, microalgae, sponges, clams, and bacteria.