Hi, and thanks!
I would say that the content on our blog (website) is indeed the best source of information on these bacteria. We there frequently cite outside (unaffiliated and therefore completely unbiased) peer-reviewed sources, which we admittedly lean on heavily since they (professional laboratory researchers) have far superior training and resources for studying these organisms. That's not to say that we don't test our products extensively; most of our research however centers around production and quality control issues rather than studying the behavior of the species, which has already been done quite thoroughly (
R. palustris and
R. rubrum for example are extremely well characterized).
All that being said, there unfortunately is no way to accurately predict the outcome of introducing these bacteria to a particular home aquarium, as each system is unique. As you noted, effects of these (or any) bacteria on algal growth rates will be highly variable from tank to tank depending upon abiotic factors including temperature, light intensity/spectrum, pH, UV exposure, even the availability of certain trace elements, and so on. Biotic factors such as competition/cooperation with members of the existing microbial community
as well as bactivory by corals, clams, copepods, etc. will further increase variability of outcome here. Even on a single tank, the effects of using these bacteria can vary over time as changes in the system occur, just as we observe with other natural methods of water quality control such as chaeto reactors, carbon dosing, etc.
For starters, I can honestly say that we never receive negative reports about them (for example, AlgaeBarn has thus far sold several thousands of units of PNS ProBio and often marvels that they have yet to receive a single bad review, which they think is pretty remarkable). I've never seen reports of PNSB exhibiting any form of pathogenesis anywhere in the scientific literature nor from our users (they're quite benign, I've even seen
R. palustris included in human probiotic formulae).
The
overall effect of using these products has proven (anecdotally, at least) to be positive, rather than merely neutral. I'd stress that these bacteria (those in PNS ProBio particularly) are intended primarily as live food/probiotics for corals and other bactivorous organisms, as it has already been conclusively demonstrated that wild corals ingest this bacterium (
R. palustris) as both a food and endosymbiont.
We thus feel that the nutritional and probiotic properties of the species alone justify its use in reef aquaria (along with some similar demonstrated benefits when added to the foods of cultured fish and shrimp).
We consider the 'other' benefits such as organic waste consumption, nutrient sequestration, competitive interaction with pathogens such as Vibrio, etc. to be qualities that simply make them more attractive as a live coral food. We do understand the strong interest in using these bacteria as biofiltration agents, and we definitely try to address all these various potential benefits to the best of our ability (our writer Taras Pleskun has a MSc. of Fisheries and Aquatic Science from the University of Florida), but we nevertheless mainly consider them to be a quality live coral food that is more likely to clean the water than to foul it.
While we've received reports from highly credible individuals of these bacteria significantly improving water quality (especially removing nitrate), we're careful not to promise dramatic (and certainly not rapid) results. In fact, one of the main advantages of this (as with other biological water quality management methods) is, in my opinion, the fact that changes occur at a slow and stead pace. Nothing good happens quickly in a reef tank, as they say. In that respect, using these bacteria to reduce phosphate concentration might be a lot safer than using, say, lanthanum chloride. Will it reduce your phosphates as much as you might desire? Maybe, maybe not, but either way, it can be a
part of a safe, natural water quality management strategy.
I know this response was a bit longwinded (haha), but I hope it helps to answer some of your very good questions. I address some of this a little more here:
If the folks at the reef discord group want to discuss this further some time, I'd love to talk to you all again.
You guys were awesome.
Oh, one more thing, the PNSB and your biopellets are likely working in tandem.
R. palustris is known to readily consume polyhydroxyalkanoates. They in fact are capable of producing it themselves as a form of energy reserve when subjected to extended periods of darkness (we use a photoperiod in the grow room to promote PHA synthesis, which presumably enhances cellular fitness and extends shelf life). Interesting side note, these bacteria are currently being investigated as a potential source of biodegradable plastics.
I felt the need to re-seed my reactor and thought this would be the best choice after previously subpar results. However, their ability to synthesize PHA is certainly an interesting tidbit!
