'anaerobic' is always bad?
Very broad statements create confusion (imo).
Avoided on the forums but consistently reported and supported as fact;
All substrate containing aquariums will have anaerobic conditions present.
Anaerobic bacteria are part of the nitrogen cycle aiding in biological balance and the last part of the nitrogen cycle chain of bacteria.
First, it must be accepted that anaerobic bacteria is always present. (Even in the gut of our fish but that is another topic.)
Only a couple documented freshwater bacteria routinely release sulfur / acid compounds based on several published papers. The remaining strains, the vast majority (numbering in the hundreds), of anaerobic bacteria only do so when presented with a lack of food (NO3). Most die without any cumulative effect. Changes in the bacter food source is the cause of this shift to sulfate production and release not disturbance alone. Normally produced is the splitting of nitrogen and O2 (oxygen).
The presence of anaerobic bacteria is almost impossible to avoid except in bare tanks with positive flow sponge filters. These systems only have the first half of the nitrogen cycle in place and are dependent solely on water changes to remove all remaining waste products. Adding plants and substrate it's an entirely different game being played in system maintenance.
Anaerobic bacteria and the production of sulfides along with acids seems to always be reported in 3 ways;
Hobbyists repeating what they have heard or read with the majority being short on facts.
Those selling products inciting fears to help do so.
Scientific study papers which are very hard for most to read. (boring and chewy)
Almost anything can be stated as toxic above a threshold limit and allowed to become imbalanced.
Controlling anaerobic conditions in a nutrient rich substrate is absolutely possible. Anaerobic bacteria factor directly into natural planted tank keeping (Walstad published method) and ages old filter systems.
Conscientious Aquarist Magazine / Seachem published copyright 2010.
Freshwater Deep Sand Beds Work by Deirdre Kylie
While some tales of anaerobic disasters surely are true, bubbles from the substrate rise too quickly and have too little surface area to sufficiently contaminate even a small tank. Itís more likely that dissolved gases and toxins from anaerobic decay were released into the water column when they were disrupted by the fishkeeper. Bubbles percolating up through the sand leave it to harmlessly close up behind them without even mixing much - this phenomenon can easily be observed in bubbles which form against the glass because the anaerobic sand is black and contrasts with the oxygenated sand.
Though my tanks are not Walstad tanks, they are inspired and informed by Diana Walstadís method and information as presented in her wonderful book, "Ecology of the Planted Aquarium." I suggest that book as a great source of information about nutrients, bacteria, lighting, etc., comprehensible to the layperson. Without it, I might have red and blue epoxy covered gravel, plastic plants, some overcrowded goldfish, and little enthusiasm for the hobby.
I absolutely agree with all these statements.
Rex Grigg's planted tank guide, D.Walstad's book, George & Karla Booth (thekrib.com) are the primary source reference for my aquarium knowledge. Expanded with experience and further reading on topics of my interest.
Anaerobic bacteria feed on nitrates not ammonia and nitrites.
Good flow and circulation through the layers of substrate will maintain imbalance but WILL NOT eliminate all anaerobic forms of bacteria nor should you want it too.
Hobby related links
(luv this site on a range of tanking topics)
Remaining Wastes topic
Link list "anaerobic bacteria + freshwater" Scholar search all articles and patents.
is what it is
I consider myself a baby on the topic of bacteria but gassing substrate doesn't scare me anymore.