[tmz]

Curious why you think there is anerobic digestion of Biopellets? This generally will be a highly aerobic environment where respiration should be the predominant mode of metabolism. Has anyone actually cultured the bacteria digesting Biopellets?

"...The bacteria will use up the carbon from the BioPellets, whilst nitrogen and phosphorus are taken from the water as nitrate and (ortho)phosphate. This conversion of organic BioPellets (together with inorganic nitrogen and phosphorus) into microbial biomass is called immobilization. In addition, anaerobic layers will develop, resulting in additional denitrification...."

The above is from the manufacturer ,here:

http://npbiopellets.dvh-import.com/



From my perspective, The bacteria that perform denitrification are facultative heterotrophs, . They use the oxygen ;form layers (mulm/film),)and; when the oxygen is depleted, use the nitrate for the oxygen leaving N to form N2 nitrogen gas. It takes very little layering for hypoxic conditions to be formed particularly with so much organic carbon available to spur their oxygen consuming growth.


Don't know why folks bounce them around so much anyway. Granted they need aeration via some flow to prevent anoxia and a lack of oxygen and nitrate leading to sulfate reduction but they ae designed for anearobic digestion:

Here is more from the manufacuters site:
How it works

NP-reducing BioPellets are consumed by bacteria, which is why new pellets need to be added every 6-12 months to compensate for digested filtermedia. This can be seen during inspection of the filter or when you measure a increase of nitrates. These figures however depend on aquarium conditions and are strongly influenced by feeding regimes and livestock. Taking regular measurements of both nitrate and phosphate levels in the aquarium is recommended, after which dosages may be increased or decreased.Of Note, NP-reducing BioPellets consist of a higher molecular mass than most competing products resulting in a longer filter retention time and thus requires less frequent refill then other low molecular weight products which are currently being marketed. Overview of biological activity on NP-reducing BioPellets. We suggest placing the outlet of the pellet filter in front of a protein skimmer, to limit the amount of bacteria entering the system. This has the additional benefit of increased gas exchange (CO2-removal and O2-addition). The pellets should never be used without sufficient aeration, as this may lead to low oxygen and pH levels, especially during night time. Proper aeration can be established with air pumps and protein skimmers. The NP-reducing BioPellets will allow more feeding (See figure) and thus more livestock, however, when heavy feeding is required, it is recommended to combine the pellets with standard phosphate adsorbents. The reason for this is that most aquarium feeds contain higher levels of phosphate than is consumed by bacteria, fish and invertebrates, when compared to nitrogen. Some phosphate adsorbents however deplete alkalinity and may reduce pH. Using phosphate adsorbent media based on iron hydroxide does not have this disadvantage. Example of nitrate and phosphate reduction in experimental 500 L tank set-up with 2 liter of BioPellets. In week 10 we doubled the feed input. You can't overdose* the NP Reducing BioPellets. Once your filtersystem is working optimal, the number of bacteria fluctuate according to the availability of nitates and phosphates. When the availability of nitrates and phosphates is low, the numbers of bacteria will decrease. When more nitrates and phosphates come available due to eg. feeding the numbers of bacteria will increase again as you can see in the example below. * When you have high nitrates levels when you introduce the NP Reducing BioPellets to your system, please click here. Example of availability of nitrates when you introduce the NP Reducing BioPellets. Up from week 9 extra feeding started which cause extra nitrate in the system. Example of numbers of bacteria after introduction of NP Reducing BioPellets. When most nitrate and phosphate are removed by the bacteria, their numbers will decrease. When more nitrates and phosphates come availeble (up from week 9 in our example) their numbers will increase again. *Number of bacteria fictive.

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