I am including biopellets in a talk im giving in Dallas next week at DMAS..
In doing so I have spent a lot of time researching them and recording what people have observed.
It appears that in most cases they do such a great job of depleting the available nutrients that corals simply starve and die.
They also deplete phosphate so well that it is likley zoaxanthellae begin to die inside coral tissue, this is what causes the death of Acropora and other stoney corals. Its likely that many other trace elements are also absorbed into the biomass they create.
To date, no one really knows which bacteria is (are) growing on them and if that a) varies between tanks, b) is actually beneficial to the tank and c) producing toxic by products.
The best results seem to be when using them sub-optimally. By that I mean in a low enough amount that they merely reduce, but not deplete the available nutrients.
One can argue that this is the same as vodka dosing a tank and that the same results should be observed, but the same results are not seen. It is likely due to selective growth of a single or a few strains of bacteria, the fact that these are concentrated in a single space and the overall effect they are having on the microbial ecology of the tank. A large enough biomass of bacteria can rap[idly deplete the tank of nutrients required for many processes.
All in all, right now- i would go gently when thinking of using biopellets and only use them if you have a problem that can not be solved by regular tank husbandry and maintenance. If a tank is designed and running well, you should not need to carbon dose, or run biopellets. Some tanks inevitably have high nurtrients- Romans NPS tank is a good example, he HAS to feed a massive amount and needs a great nutrient export system and biopellets deal well with this. In general a regular reef tank should be able to proces its own nutrients.
anyways--- those are my thoughts based on a lot of reading and chats with a bunch of the people in the hobby.
Regards,
Paul.
