I agree, it is very interesting.
I wonder how accurate it is? Strange that it shows no Nitrite processing bacteria and very little Ammonia processing bacteria.
Hi all,
We're also discussing these results over here, I link it here just to keep everyone in the loop
https://www.reef2reef.com/threads/i-had-my-water-tested-but-need-explanation.668326/
Your question about accuracy is an important one. My overall response is that the measurement is very reproducible, and also pretty sensitive. If a microbe (Bacteria or Archaea) is present in Pauls sample at a level of at least ~1 in 10,000, we will detect and identify it. The biggest limitation is sampling - if it's not on the filter or swab I can't detect it.
We should not conclude these were absent, but rather they were below the limits of detection within the sample. There is more variation in the levels of nutrient processing microbes across tanks than I would have expected when I started this endeavor.
Now details in support of the above. Here is a figure that shows the communities in 2 experimental tanks side by side (A and B). A1 and A2 are two samples from tank A. As you can see, duplicate samples are very very similar, showing that the measure is highly reproducible.
My statement about sensitivity is based on the number of DNA sequences produced for each sample. (about 10,000 DNA sequences per sample). We can think about this as drawing marbles out of a bag that contains millions of marbles with hundreds of different colors. If we draw 10,000 marbles, we can be confident we'll collect all the most common colors. But a super rare marble , 1 in a million, is unlikely to be detected.
So I am confident these microbes were not present at high levels in Paul's sample. We sampled water and biofilm from the inner surface of a pipe (I chose the latter because every tank has pipes of some kind, and NOB are known to accumulate in the biofilm of pipes in water treatment plants). In many tanks I sampled, both of these samples contain ammonia-oxidizing and (AOB) nitrite oxidizing (NOB) microbes at low but very detectable levels (up to 6% AOB and 0.4% NOB). Not Pauls. And also not my 4 home aquariums.
The variation surprises me a lot but I've learned not to discard findings that surprise me. As often as not, its my expectations that were wrong :)
I think the physical sampling of the tanks remains the most important area to explore for these particular bugs, rather than any general methodological issues. But its clear there is real variation among tanks here. The question I'm asking is, are they rare everywhere in my tanks (and Paul's) or are they localized in a different part of the tank in our tanks than others? Its hard to understand why the latter would be true but I can't rule it out.
