Your hypothesis based on your life experience and knowledge leads you to believe that organic material will sink into a DSB
We need not "believe" that organic matter will sink into a DSB. "Belief" should be reserved for religion. Not science. The basic laws of physics tells us that organic matter sinks. Organic matter is typically heavier than water. Therefore, it sinks. We do not need a dedicated scientific experiment to show this. The science involved is well known and well understood. To "believe" differently is to simply be wrong.
If you must have an experiment to show this process, it's simple. Take two white buckets and a gravel vac. Siphon water from the mid water level of an aquarium, into bucket "A". Then siphon water through an aged Shemik style DSB, using the gravel vac, into bucket "B". We can not see through organic matter. The bottom of bucket "A" should be clearly visible due to the lack of organic matter. Bucket "B" will be so choked with rotting organic matter that the bottom of the bucket is not visible. The sand was clean when it originally went into the aquarium. How did the organic matter get in the sand? . It didn't just magically appear. It settled, and accumulated there due to the well know laws of physics. This isn't arguable. It can not be disputed. It is fact.
and create these byproducts which will then lead to a loss of livestock.
Again, this is well known and well understood science. One organisms waste is anothers beneficial nutrients. This is the process that makes life possible on this planet. Our waste is toxic to us, but not to some other organisms. We must separate ourselves from our waste or die. If your kidneys fail, you're dead, because you are no longer able to separate yourself from your waste. If you relieve yourself in your bedroom, and allow your waste to accumulate there, you're likely to get sick and die. If you relieve yourself on your lawn, you're likely to have some lush green grass, because the grass is able to utilize your waste as beneficial nutrients. If we force our pets to live in a tiny glass box with six inches of their own waste accumulated on the bottom, they're likely to get sick and die. This is nothing new. It's well understood. We clean the bottom of every other small container where we keep living animals. Hamsters, birds, snakes, humans in jail............... you name it. If we do not remove an animals waste from the small container where they live, they are highly likely to get sick and die. This is fact. It is not arguable. This is not a "hypothesis". This is not a theory. This is well known fact. To "believe" otherwise is simply absurd.
Other noted scientists have written extensively explaining their hypothesis that such organic material will remain in suspension due to the high flow rate found in many marine aquariums and so the organic material will be removed as a matter of routine maintenance and skimming thereby allowing the sand bed to remain biologically active.
Who are these "noted scientists", and where is their work?
There is no scientist, worth their salt, that would make such a statement.
If the flow is slow enough to allow the grains of sand to remain stationary on the bottom of the tank, it is also slow enough to allow particles of organic matter to settle and accumulate there as well. You would have to increase flow, to the point that inorganic particles could not remain stationary, to prevent organic particles from becoming stationary. Stationary particles of sand obstruct flow, slowing it to the point that organic particles carried into the sand with that flow, settles and rots. The only way to prevent this, would be to increase flow to the point that sand itself was no longer stationary.
examples exist of BOTH healthy DSBs and stinky, sludge filled DSBs. Why? We don't know.
What is your definition of a "healthy" DSB? And healthy to who?
It's been explained before. A sand bed that is deep, need not be "unhealthy". We simply need to keep it clean. A sand bed, as Shemik describes it, where we allow "sludge" to build to the point that it supports hundreds of thousands of sludge eating organisms, will becomes unhealthy for the pets we purchase.
Can you quantify how much biomass remains from feeding 10 fish?
Why is that relevant? We know that the more biomass we have in a system, the harder we need to work to keep the system clean and healthy. The lower the biomass, the longer the tank will remain healthy without our intervention. We really don't need to put a number on the amount of biomass produced from feeding "X" number of fish. We simply need to understand the importance of keeping that number as low as possible.
Is the biomass leftover from herbivorous fish the same as that left by carnivorous fish?
No, but again, it's really not relevant.
Are any of these byproducts different from the byproducts created when human waste breaks down,
Not any more different than the rest of the animal kingdom. The waste produced will vary from species to species and from day to day. The waste I produce today will be different from the waste I produce tomorrow. I seriously don't see where this is relevant though. All of this waste material contains many different elements and compounds. As this waste breaks down, the substances it contains will be altered and released back into the environment. These substances are beneficial to some, and toxic to others. This is one of the reasons we have different habitats in nature that support different forms of life. Mangrove swamps have high concentrations of these substances, due to the large amount of rotting organic matter in the sediments. There are times you can smell a mangrove swamp from miles away. The organisms found in mangrove swamps differ greatly from those found on healthy, growing, coral reefs. The concentration of substances released through decomposition are very, very, very, very, very, low on these healthy coral reefs. This should be a HUGE red flag to anyone attempting to keep coral reef creatures in a tiny glass box. Keep large amounts of rotting organic matter in the tank, and you create something that resembles a mangrove swamp. Remove rotting organic matter and you're more likely to create something that resembles a healthy, growing, coral reef.
If biomass does accumulate what is the rate of accumulation, can that rate vary from tank to tank,
Yes. The rate of accumulation will, or can, differ greatly from one system to another. However, the rate of accumulation is irrelevant. If I drive to work a 50 MPH, I'll get there quickly. If I drive 5 MPH, I get there slowly. It doesn't really mater because I end up at the same place. If I accumulate one cubic CM of rotting organic matter in my sand per week, it may take quite some time before it becomes unhealthy for my pets, or causes me to invest in a larger skimmer. If I accumulate ten cubic CM's of rotting organic matter in my sand per week, it will become unhealthy much faster. I don't need to have a number to represent the rate of accumulation. I simply need to understand that I need to limit that accumulation, and/or take steps to offset the negative effects of that accumulation.
We know that it accumulates, not only because we see it with our own eyes, but because we typically feed at a rate that exceeds the rate of decomposition. In other words, if we feed a cube of food, we typically feed another cube before the first cube has a chance to completely decompose. A portion of that food will end up in the sand bed even if we have an incredible filter system.
Nature is great at supporting massive amounts of life, and creating very nutrient rich environments, with very little nutrient inputs from outside sources. In our system, what starts out as a little detritus in the sand bed, can become a nutrient laden swamp, if we do not intervene to stop this process. Bacteria will take up nutrients from that detritus and reproduce. Bacteria can be short lived. When they die, their tissues are added to the rotting organic matter in the sand along with the small amount that gets there through the food we feed. Now the living bacteria are utilizing nutrients that originate from the foods we feed, and the tissues of their dead relatives. As this process grows, the amount of nutrients being released into the system water grows. It begins to fuel algae and microbial growth in the rocks above. When these organisms die, they fall into the sand, where they rot and fuel more growth/reproduction. As the amount of organic matter grows, it begins to support larger animals like worms, and mini crustaceans/pods. These organisms don't typically live long either. They grow, reproduce, and die, just as the algae and microbes do. Through this process, nature is able to recycle nutrients in one area, increasing the nutrient content of that area, even when the input of nutrients to that area is very low. This is clear to see in photos of Shemik style DSB's. There is an abundance of life in these sand beds. Everything from cyanobacteria, worms, pods, algae, and countless little critters not viable with the naked eye. This proliferation of life could not be possible if it relied solely, and directly, on the food being added to the aquarium on a daily basis. It's only possible due to natures ability to retain and recycle nutrients in one area. In a Shemik DSB system, on day one, everything is clean, and the nutrient level of the system is low. As time progresses, the nutrient level within the system continually climbs. The common scenario in these systems is for the filtration and maintenance to cope with this pollution for a period of time. The health of the system is constantly being degraded, but the filtration and maintenance handles it. Eventually, the system reaches a point where the production of harmful substances from rot and decay overwhelm the filtration's ability to keep those levels low. This is when animals die. People declare the system is suffering from old tank syndrome, and needs to be started over. Often, the hobbyist "belief" in this system is so strong, they break down the system, and rebuild it, doing the exact same thing again. This only leads to more animals dying, and thousands of dollars needlessly spent.
and how long will it take at the maximum rate of accumulation before enough hydrogen sulfide is formed to create a deadly release of gas. 1 year, 5 years, 50 years?
While hydrogen sulfide is a reasonable concern when talking about harmful substances from decaying matter, it isn't needed to cause illness and death in our systems. Any number of elements, compounds, or combination of substances released/produced through decomposition can reach harmful levels when you have six inches of rot and decay on the bottom of the tank. Most elements are at trace levels on coral reefs. Some down to the parts per billion.
and the fact will still remain that healthy tanks with DSBs exist.
You have stated that this is not evidence proving DSB's are beneficial, yet you keep bringing it up, and even posting pic's of tanks with DSB's, as if it proves something. It does not.
Most people would agree that dumping liquid fertilizer, full of nitrogen, phosphorus, and heavy metals into a reef tank would be a bad idea, and put the lives of the inhabitants at risk. However, I could hook up a dosing pump to dose such a fertilizer into my system, and still have a seemingly healthy and thriving reef display. I simply need to employ methods to remove that fertilizer at a pace that keeps the concentration of harmful substances below problem causing levels. The question is, why would I do that? The fact still remains that such liquid fertilizers would be harmful to coral reef tanks. Six inches of rotting organic matter on the bottom of a tank will release fertilizers like nitrogen, phosphorus, and heavy metals. Just like the liquid store bought fertilizers. So, the question is, why would I put such a sand bed on the bottom of my tank?
All we can say is that some people with DSBs are making it work.
No. We can not say that. The fact that they have a DSB, and all their animals haven't died, is not evidence that a DSB works. Shemik and his disciples have made some outrageous claims about the magical abilities of their DSB systems. If a DSB does not preform these tasks, they do not work. If I pile up a bunch of scrap metal in my front yard, and claim it to be a rocket ship to the moon, can I claim that it works if it can not fly to the moon? Of course not. It's just a pile of junk in my front yard. This DSB does not perform the tasks claimed of it. Therefore, it does not work. It doesn't matter that a DSB hasn't killed every living creature in some tank somewhere. It still does not work. It's still nothing more than a six inch pile of rot and decay full of worms and bugs.
Peace
EC:beer:
