how long is the life period of sandbeds

[Geoff]

even sand sifting critters poo. eventually the poo has to be removed.

if the SB is shallow enough that you can siphon parts of it out without releasing clouds of detritus or hydrogen sulfide than you can change parts of it out on occasion.

as for the ocean floor. have you ever heard of phosphate mines? look up phosphate mining i have a feeling it will be an eye opener for you. then there is the whole plate techtonics thing that seems to renew the ocean flow on occasion. there is only one reason why cyano is not completely covering the bottom of the ocean, no light.

G~

[tdwyatt]

Originally Posted by jenajet

Um not really phil. The sand can only go for so long before it is full. I can't go into the technical stuff, maybe Tom will stop by. You need to list age & size of tank, critters, test numbers, lighting and such. That will all play a part in how long you can keep the sandbed.

Question answered, though I see where Geoff has gone into a bit more detail. The problem is that here is nothing for the bacteria to push against (literally) as there is with live rock, so the detrital remains end up accumulating in the DSB over time. With live rock, the detritus of bacterial flock ends up being pushed from the rock, and can either be suspended in the water column with turbulent flow under the rock and either skimmed out or siphoned from eddies in the tank or directly off the rock. Sand, unfortunately, does not offer us such a luxury, and becomes the compartment of accumulation as dead or recycled bacterial biomass as end-detritus begins to make up a greater percentage of the total mass in the sandbed over time...

As Jen, Geoff, Platy, et.al., have already pointed out, it will depend on how quickly nutrient/phosphate imports exceed exports in time, and how good a job at preventing end-saturation of the sand with phosphates you can do with your husbandry skills. As much as I hate to admit it, there are no means of preventing the end-saturation of calcareous sands with phoshate from occurring, as we do not have a means of exporting adsorbed phosphate from the calcium carbonate sands short of removing the sand altogether. If you can solve THAT issue, then maybe we can have sandbeds that do not require an ultimate removal and replacement with new sand. Until then, that is the state of sandbed lifespans for now.



HTH

[tdwyatt]

Originally Posted by Geoff

...there is only one reason why cyano is not completely covering the bottom of the ocean, no light.

G~

Actually, there are now complete ecosystems of new forms of life that do not use ANY light to drive autotrophic mechanisms of bioactivity. Some use heat, some use chemical energy potentials, others use different electron receptors than O2, but they are all different from photoautotrophic life and its attendant heterotrophy and employ the huge accumulations of chemical nutrient potentials that exist at the sea floor. The only reason that THESE biotopes don't cover the bottoms of our tanks rather thn cyanobacteria is that our tanks are too young...


Much like politics, Nature abhors a vaccuum.

[SPC]

Originally Posted by Geoff

as for the ocean floor. have you ever heard of phosphate mines? look up phosphate mining i have a feeling it will be an eye opener for you.~

,,,and then there is the question of where the media for calcium reactors come from too .

Another thing to keep in mind, Phil, is the many different environments of the ocean. If our tanks DSB trully represented the natural reef DSB, there would be no build up of organics like we see in our tanks, and any low flow high organic system in nature (the low tide smell and lakes turning over are examples of this).

then there is the whole plate techtonics thing that seems to renew the ocean flow on occasion.

Exactly, and even with this the detritus will be stored in the abyss over millions of years. I read an article a while back that speculated some of the mass extinctions on earth could have been caused by the abyss "burping" up a large amount of methane.

Steve

[AquaGrizzly]

Does having a plenum help extend the life of the SB? Also what is the benefit of having a plenum? Are they good to have or not? Sorry if this high jacks but it does pertain to the topic.

[SPC]

Originally Posted by AquaGrizzly

Does having a plenum help extend the life of the SB? Also what is the benefit of having a plenum? Are they good to have or not? Sorry if this high jacks but it does pertain to the topic.

Several main differences (please note, the following are according to the people credited with the developement of each system).

- A DSB requires a sugar fine sand with a silt size being even better. A plenum uses a much coarser substrate.

- A plenum should be vacuumed as part of regular maintenance. A DSB should never have any vacuuming done.

- A DSB requires the correct species, as well as numbers of bugs be kept in the sand (this can be accomplished with a microscope and a "bug" identification book used a minumum of once/month). The bugs may need to be fed extra if they don't obtain enough nutrition from the tank. A plenum requires no life in the substrate to function correctly.

- A DSB tank should never contain any creatures that would eat the "bugs" in the sand (example, sand sifting gobies, star fish, many species of shrimp etc...), unless there is an ample amount of "bugs" for both the DSB and the "bug" eaters. How is this determined? Your microscope and "bug" book will need to be used until the correct ratio is reached, and then used again as the "bug" eaters grow and/or the "bug" population increases and decreases, and then used again...

Both systems work, but IMO the plenum may achieve a longer life before it goes sour.

BTW, there was a very long thread on RC a few years back (and just recently resurrected) that proposed a DSB/plenum combination where the waste water is removed on a regular basis.

Steve

[tdwyatt]

Originally Posted by SPC

- A DSB requires the correct species, as well as numbers of bugs be kept in the sand (this can be accomplished with a microscope and a "bug" identification book used a minumum of once/month). The bugs may need to be fed extra if they don't obtain enough nutrition from the tank. A plenum requires no life in the substrate to function correctly...

ahem....


I am sure we will take this as tongue-in-cheek... Although it may be true to some extent, and I am sure we are not looking for a DSB right-vs-wrong protocol discussion here... I will just say that the details are not that clear , and seeding the sand bed is usully best ccomplished by just getting a number of sand samples from different sources, rather than going to the point that we ID the bugs in the sand. look in particular for sandbeds that do not have cyanobacterial growths (greater chance of cyano competition and consumers in the sand biota). Usually just assuring the presence of bugs in the sand, then gathering diversity from a number of sources is enough to insure a well-functioning DSB so long as nutrient restriction is practiced with good export and the DSB is deep enough (12 to 15cm), of fine enough granule size (sugar sized and down), and left undisturbed.

However, this protocol has been developed through trial and error, and there have been few if any objective studies to really delve into what works the best for these biologica filter compartments, so you will have to take discussion on the topic with a proverbial grain of IO salt...


Sorry to step in like this Steve, I felt a DSB discussion moment coming on (much like a migraine aura...)

[salt-rookie]

Geoff....I RESPECTFULLY disagree. Phosphates and sulfates on the ocean floor come from a myriad of sources, LEAST of which would be anoxic organics from fishes. The GREATEST source would be from volcanic magna when fissures occur on the ocean floor.

I've been in this hobby since December, 1963 and to debunk the DSB is to also debunk the UG filter in freshwater. Detritus is processed by anaerobic bacteria and rises to the top and is dissipated into the atsmophere as harmless methane and nitrogen gasses.

The parts of the ocean floor of which I speak are those occurring immediately below the coral reefs of the world...aragonite DSBs that are 100s of 1,000s of years old and NEVER vacuumed out.

When I did my doctoral disertation and the defense thereof...I would NOT have been granted my Doctorate had I NOT been able to defend my work without any reasonable doubt. THIS is why I believe Shimmek is a BAFOON! This is MY opinion, you don't have to agree, and I won't try to change your mind, but you won't change mine either...I'd call this process mutual respect.

[tdwyatt]

Originally Posted by salt-rookie

Geoff....I RESPECTFULLY disagree. Phosphates and sulfates on the ocean floor come from a myriad of sources, LEAT of which would be anoxic organics from fishes. The GREATEST source would be from volcanic magna when fissures occur on the ocean floor.

I've been in this hobby since December, 1963 and to debunk the DSB is to also debunk the UG filter in freshwater. Detritus is processed by anaerobic bacteria and rises to the top and is dissipated into the atsmophere as harmless methane and nitrogen gass.

The parts of the ocean floor of which I speak are those occurring immediately below the coral reef of the world...aragonite DSBs that are 100s of 1,000s of years old and NEVER vacuumed out.

Not to throw a wet blanket on your claims re: where the oceanic phosphate deposits come from, but you should check your facts. See the recently published text The Ecology of Hydrothermal Vents as well as the text studies in turbidite systems which directly relate to our discussion here (I have linked some info on how these systems work here.). There is already enough misinformation regarding this topic out there, lets not add to it with unsubstantited claims.

If you would like, I will gladly document how much of these deep oceanic recycling systems work once the East Coast Picnic is done (next week), but these systems do not work as we see DSB proposed as in shalllow (< 1m) tanks. Much of how the Deep recycling works DEPENDS on the tremendous pressures found at depths greater than 4000m, as well as the chemical depth profiles associated with most substances as depth increases (see James Millero, Chemical Oceanography )

I am open for a good dicussion, but not for unfounded and unsubstantiated poo flinging based on suposition in the face of available factual information, I will be glad (as I am sure that Timmah will too) to offer text passages and papers discussing how these systems work for open disecussion of these systems.


JMO

[Geoff]

most of the tropical areas of the world also suffer from tropical storms. these are great at cleaning out detrital buildups on a very large scale.

in FW system it is a known fact that they need to be cleaned out on a regular basis. for some silly reason people feel SW does not need this.

G~

[Fly Guy]

Originally Posted by SPC

Your microscope and "bug" book will need to be used until the correct ratio is reached, and then used again as the "bug" eaters grow and/or the "bug" population increases and decreases, and then used again...

[salt-rookie]

I guess it depends on which EXPERT's writing you read.....

[mantisfreak]

I'm not going to get into this argument because you both have your opinions and I'm not going to change them.

I do want to point out the following to the original poster. Ocean sediments are considered a major influence on the phosphate cycle, Sulfer cycle, and the Carbon cycle.







Additionally, DSB's do not work like in the wild. I was talking with Dana Riddle a couple of years back. They had a storm and the cove that Dana had been studying for years was emptied of every single grain of sand. Even very large corals were gone. Within a fairly short period of time the sand was returned by the tides. Our DSB's never get these complete CTRL-ALT-DEL restarts and just continue accumulating nutrients. Dr. Ron discussed this issue back in 2003.

The absolute position of the sediments will often vary from season to season, particularly in intertidal and shallow subtidal areas. Tourists who always visit a given resort at a particular time of year are often quite amazed when they return to the resort six months out of sync with their usual pattern and find the sandy beach they expect to see has vanished, leaving a hard coral pavement instead. Movement of sediments is less in deeper waters but it still occurs. In fact, one major characteristic of natural sand beds is their mobility.

[tdwyatt]

Thanks for the post, Curt, this is actually exactly where I will be going on the topic after the picnic.


DSB work NOTHING like the wild, closed systems have their own sets of limitation and laws of operation as has been pointed out in the biosphere work by Ted MCCONNAUGHEY, et.al., it's those darn laws of conservtion of matter that seem to get in the way the most...

[SPC]

Originally Posted by tdwyatt

ahem....


I am sure we will take this as tongue-in-cheek... Although it may be true to some extent, and I am sure we are not looking for a DSB right-vs-wrong protocol discussion here... I will just say that the details are not that clear , and seeding the sand bed is usully best ccomplished by just getting a number of sand samples from different sources, rather than going to the point that we ID the bugs in the sand. look in particular for sandbeds that do not have cyanobacterial growths (greater chance of cyano competition and consumers in the sand biota). Usually just assuring the presence of bugs in the sand, then gathering diversity from a number of sources is enough to insure a well-functioning DSB so long as nutrient restriction is practiced with good export and the DSB is deep enough (12 to 15cm), of fine enough granule size (sugar sized and down), and left undisturbed.

However, this protocol has been developed through trial and error, and there have been few if any objective studies to really delve into what works the best for these biologica filter compartments, so you will have to take discussion on the topic with a proverbial grain of IO salt...


Sorry to step in like this Steve, I felt a DSB discussion moment coming on (much like a migraine aura...)

Please go back and look at what I wrote at the begining of my post,(please note, the following are according to the people credited with the developement of each system). This was put in there just for guy's like you that disagree with the DSB expert.

Steve