Hi all,
I try to not delve too deep into the science............
I really like to know how things work, but I'm not sure it necessarily makes <"
you a better aquarist">.
That was really the reason for the development of the <"
Duckweed Index">, it is a simple methodology and it hides all the <"
interesting / scary bits"> under the bonnet. All you need to do is <"
watch the plants">.
It is the same with "
plant and wait" <"
tank cycling">, you aren't reliant on making decisions based on things you can't see, again all you have to do is watch the plants.
I know from my "day job" that a <"
visual approach"> works much better than a numeric one for obscure concepts and I think that both plant growth and <"
cycling"> are obscure concepts. We can't see <"
the ions in solution">, or the <"
microbial community"> in the filter etc., but we can see <"
their effects">.
A criticism has been that they aren't <"
very scientific approachs">, because you don't have empirical proof and numbers, but since I've worked with Ecologists and <"
Freshwater Biologists"> I've began to realise that we can also use concepts like Biotic Indices, and that they are <"
sensitive metrics">.
Some non-essential conjecture.
First the bit <"we know">, that the nature of that <"microbial assemblage"> is <"fine-tuned over time"> to reflect the levels of ammonia (NH3) and dissolved oxygen in the water.
This would be conjecture, but I visualise the microbial assemblage in a filter in the same way that I think about the <"benthic invertebrate assemblage in a stream">. In clean water (water with a lot of dissolved oxygen and a low Biochemical Oxygen Demand (BOD)) you have a diverse assemblage of invertebrates, including <"Mayflies (Ephemeroptera), Stoneflies (Plecoptera), Caseless Caddis (Trichoptera) etc."> with Tubificid worms (Naididae) and "Bloodworms" (Chronomidae) etc present, but as a minor component of the assemblage.
As pollution (BOD) increases dissolved oxygen levels fall and you lose the more sensitive species from the assemblage. At the same time the number of Blood worm and "Tubifex" increases. As pollution continues to increase eventually only the haemoglobin containing Blood worms and Tubifex are left, and these often <"build up to huge numbers">.
The "Tubifex and Blood-worm" scenario is the traditional view of "cycling", with Nitrobacter winogradskyi etc representing Tubifex etc. If you only ever look at sewage treatment works? You never find the Mayflies.
cheers Darrel