dosing vitamin c

FishBrain (Bill) has reported success with vitamin C as a dosing medium. I also maintained my tank using vodka (ethanol) for the course of a year with good results. Eventually though, I was lacking dilligence with my dosing regime and reverted to traditional methods to maintain water parameters.
However, recently I've been reviewing some of the literature on probiotic systems and organic carbon dosing, and some things have been brought to my attention. Regarding vitamin C (ascorbic acid), although they are popular among zoanthid keepers, and there are other (perhaps anecdotal) reports of success, ascorbic acid has a pka of 4.1 and will likely oxidize in seawater producing hydrogen peroxide (an anti-microbial). Fortunately H2O2 precipitates at low temperature, and will likely boil off and deposit the remaining methyl + aromatic carbon as substrate for bacterial populations. The implication is that there is a high risk of over dosing with vitamin C, and it actually (volume for volume) deposits less carbon than other dosing systems.
Also, remember that organic carbon dosing does not drive coral growth, it is utilized as a system of driving nutrients (NO3 and PO4) to ultra low levels, enabling the aquarist to feed corals heavily, and thus providing a more natural environment for many scleretarians (sps). The use of GFO in conjunction with carbon dosing regimes is not recommended, rapidly decreasing of any water parameters and bacterial saturation can lead to coral stress, when dosed regularly, organic carbon regimes are effective in and of them selves and driving phosphate and nitrates to unmeasurable levels (using some of the most precise test kits such as LeMotte).
All carbon dosing regimes should employ the use of a good skimmer, which will remove free floating (expended/dead) bacterial colonies as they exhaust themselves consuming nutrients. Essentially, carbon dosing regimes are much like growing macro algae, (and much like baking a cake). Removal of excess bacteria (macro algae) is removing the biomass in which phosphates and nitrates are deposited, this is done via the protein skimmer in bacterial driven systems. Carbon is simply the limiting reagent for bacterial growth, in a paper published circa 1929 (I don't recall the exact dates) researchers described the assimilation of phytoplankton colonies to be in a 106C:10N:1P (carbon/nitrogen/phosphate) ratio, nicknamed "the redfield ratio." This is the foundation (and much forgotten) of carbon dosing systems as we know them today.
Last but not least, although I know a number of aquarists who achieve good results using carbon dosing systems alone, as a biologists (thereby understanding population dynamics) I can't stress the importance of bacterial additives enough! Competitive exclusion is a mathematically proven theory (should be a law, but because of the dynamics of selection in biological systems isn't always reproducible) and long-term, perhaps over the course of years, one bacterial species will drive the others to extinction. This is problematic because different types of phytoplankton/bacteria/flagellates etc. which are benefiting from a carbon regime synthesize nutrients at different rates (ratios). In this situation it is possible that nitrates become a limiting reagent, and the removal of phosphate is thereby inhibited. Thus necessitating the addition of bacterial additives such as ZEObak, BioDigest, MicroBacter7, etc. for the maintenance of robust bacterial diversity.
Sorry for the lecture, but I thought some additional input may be useful for others.
Cya guys,
-ANdy
edit: I might add, some reports I ran across recently suggest that regular feeding of scleractinians can enhance the production of calcareous matrix 60%! re-enforcing the notion that if we want our corals to grow, we must feed them particles of the appropriate size and composition. The great thing about bacterial driven systems, is that they really enable us to go nuts with feeding!

 

I enjoyed your lecture thanks Andy!!!