The problem with DSBs

[Paul B]

Fiskisser, I just wrote this on another Forum to answer a similar question. I think it will fit here also.
I think I also explain why even adding microorganisms IMO will not help. I think the only thing to do with such a bed is to remove some of it in a few years, clean it and put it back.

Don't forget, this is my theory and mine alone. I take full responsibility and know that most, if not all hobbiests will disagree. In 20 years we will know the truth.

The technology as to how they work is not flawed, but the technology as to what keeps them working is flawed.

DSBs have been around for 20 years or so, where are the tanks that ran these systems 20 or even 15 years ago?
There are a handful of even 10 year old DSBs. I know of two.

Any substrait in a closed tank will fail eventually. Even my RUGF.
The difference is the size of the particles. Smaller particles will clog sooner. The theory of a DSB is that organisms populate the sand and burrow down to the lower levels there by letting in water to be treated by the bacteria to remove nitrate.
Everyone knows that will work, initially. As the bed matures and detritus accumulates, which is composed largely of dead bacteria, the anerobic or anoxic areas (yes I know they are different and I called Bob Goemans to tell him of his mistake)
Can not support any life except for certain bacteria.
Pods, worms, crabs, or anything else can not live there nor can they visit there even for a few seconds. Eventually, that layer will not have any water circulation and it will become anoxic. Totally useless for our purposes because no water can get there to be treated. There is no animal life there due to no oxygen. The spaces between the sand grains will clog with dead bacteria and detritus and if you drilled a hole in the bottom of such a tank, I doubt any water would leak out.
The waste materials that get treated in a DSB do not magically get beemed to another dimension. There is always some solid waste materials in an aquarium and it does not take much of this to clog sand.
Another thought is while these organisms will dig in the substrait, after a few years many of these minute animals will no longer re produce. After a short while most of the bed will be very barron.

 

[Clownfish518]

Paul,

You are so right in saying that we will know how it works down the road. Time will tell whether what you think or I think is correct, or if we are both wrong and reality is something completely different, which is what I suspect.

 

[fishkisser]

I have been of the opinion that DSB's were the way to go but this article has given me so much "food for thought" I think I might choke! The article is in two parts.:columbo:

Welcome to Saltcorner.

 

[Clownfish518]

Yes, I read that, I think Bob doesn't have his ducks lined up at all and that article is misinformation

Anyone who wants to propose a scientific theory needs to follow the scientific method; they need to get published in a journal (such as Advanced Aquarist or Coral) and undergo peer review, not get published in a newsletter distributed by a manufacturer. Whether Bob is right or wrong, its poor science

 

[fishkisser]

Yes, I read that, I think Bob doesn't have his ducks lined up at all and that is misinformation

Truth be told clownfish518 I lack the required scientific training to make a TRULY INFORMED judgment and even if I has such training i would just be another credible source in the difference of opinions.
Therefore I am relegated to following that which instinct tells me has made the best argument.
Can you tell me exactly what specific elements you believe are flawed in the bi-authored article? I have not made a decision and would like to know your concerns.:columbo:
Thank You,
benjamin

 

[fishkisser]

Mitch, I copied this post from another forum, Too much typing.
The algae trough was an experiment that I kept in there. It is just a PVC fence post cut lengthwise that sits at the top and towards the rear of the tank. Part of the main lighting enters the trough and there is a plastic screen in there that can be easily rolled up and removed to clean if necessare. The thought is that the algae growing conditions are better in the trough and if algae wants to grow, it will grow there. I feel algae is a benefit to the inhabitants so I like it, I just don't want it on my corals. Algae is the best nutrient remover there is and it's natural.

Here is that post about UGFs

The reason why no one except me uses one is because in the eightees we started getting "experts" in the hobby. Some of them were from Europe and they used regular UG filters, (as I did) and they crashed, or at least in a year you had to tear the thing apart to clean it as it would clog miserably. (as mine did)
The then new experts decided that UG filters were no good for salt water and came up with Jaubert systems, Berlin systems and natural systems. Natural systems depend on you living on a tropical beach so I won't go into that.
Many books were written on the benefits of each and each one definately has advantages. They actually evolved into DSBs of today.
So the UG filter was banned from the hobby as being useless.
And it is if you follow the directions that come with it.
None of the resident "experts" would touch them because the other two systems were the sexy in thing and UGs were around from the early fiftees. (before the experts were born)
But Aha, then came me, I reversed the thing, put a filter on the intake and ran a big powerhead on it. After a couple of years it also filled the gravel with detritus forcing me to stir up the gravel and suck out the crud. The nitrates were also high, around 20.
So I drastically slowed down the flow and it went 25 years without me cleaning under the plates. Now I slowed it down more and I feel it will go 30 years before I may have to clean under the plates, maybe never. I will be 90 years old then and probably more interested in baby food than fish so who cares?
Now my nitrates stay around 5 and everything spawns, ich does not live in the tank so I don't have to quarantine, some fish live for over 18 years and the corals seem to be "happy"
I don't have hardly any SPS corals as I don't have a lot of luck mixing them with leathers and LPS. I don't mean for a couple of years, I mean longer than that. Anything will live a couple of years, even in Waterkeepers tank
So now we have thousands of tanks that are set up with DSBs.
I hope they last forever because a DSB can not be maintained.
It actually depends on you not touching it. You can of course remove some of it and replace it which will make it last forever,
I think, no one has an old one so we don't really know yet.
Another advantage of a RUGF is that I can push corals or rocks deep into the gravel, all the way to the UG plate if I like without doing any damage. I also can create a typhoon with a diatom filter to powerwash the rocks as happens in the sea and suck out any detritus causing the tank to be completely renewed.
The spaces between the gravel grains become filled with tiny tube worms and pods. Tube worms are filter feeders and will effectively eat any food particles that get pushed under the gravel.
The nitrates get eliminated due to the interfaces of the gravel that in time aquire some detritus limiting oxygen. Don't forget the water is flowing very slow.
Each gravel grain is an entire town to a bacteria and in a few weeks oxygen in limited in between the grains.

OK I think I explained the hell out of that.

The question is begged in my mind: UG with DSB on top???

 

[Clownfish518]

"...there are nitrifiers and dentrifiers and both can live in the same environment, and some are facultative anearobes. Third, sand beds are limited in size. A coral reef, even if all nitrogen was converted by denitrifying bacteria in sand beds, which it isn't (note extensive discussions on algal uptake of N, and any paper on eutrophication), a coral reef is a ribbon of substrate surrounded by vast fields of seagrass 100X the size of the reef, and sand both in front of and behind the reef 10s of thousands the size of the reef (see thread on hypothetical ideal), and a couple billion gallons of water. The sediments denitrify, but denitrification proceeds at a slow pace compared to nitrification, why the sand space is 10s of thousands of times the reef space and also ignores the bejillion other factors, not the least of which is the use of N by N-limited species, notably algae (see thousands of papers on nutrient enrichment and herbivory).

That said, if the tank runs right, a sand bed in conjunction with proper design and stocking, can help a lot. The use of a pure sandbed as the sole means of controlling nitrate in every tank was and is possible, but is hardly likely and we have known that for fifteen years. On the other hand, I can name tanks with and without sand beds, with or without bare bottoms, with or without skimmers, with or without any other method used that still have either unmeasurable or problematic nitrate levels. Why? Because every tank and aquarist is different, and the biota is different, but biological processes are the same. That's why the Florida Keys don't look like Galapagos which doesn't look like Heron Island. Most people want Heron Island, but the conditions are different yet the same biological and ecological processes are occurring...

Rapid nitrification in oxic environments and slow denitrification in special areas of oxic environments
Slower denitrification in hypoxic areas and anoxic areas with some nitrification (percent wise, not speedwise)
Nitrogen fixation is also taking place.
Sulfur reduction certainly in reducing areas and in special areas in other environments
Sulfur oxidation also coupled within the benthos in more oxic areas.

In the most abridged incomplete summary


I mean, every worm that eliminates produces ammonia in the sand bed, and this extends to metabolic activity of microbes, as well. Some - and depending on the sand and the oxygen state, use it as fuel, and some not. And, when I said "locally" I mean that some processes may be happening on the surface of a sand grain and others in a crevice or pore of a sand grain."

Eric Borneman, President of MASNA

 

[Clownfish518]

The question is begged in my mind: UG with DSB on top???

Take a look at Jaubert systems. They do work, though are not much in vouge ATM. A plenum of anoxic water underneath a DSB. The plenum is easily constructed by a UGF. I was in love with mine - started one in the early 90s and had it 12 years or so, never had any nitrates

 

[fishkisser]

Take a look at Jaubert systems. They do work, though are not much in vouge ATM. A plenum of anoxic water underneath a DSB. The plenum is easily constructed by a UGF. I was in love with mine - started one in the early 90s and had it 12 years or so, never had any nitrates

If the idea is to create the largest LOW oxygen area possible why not the DSB with a UG and a very slow flow? In theory all sections of the DSB would receive "some" oxygen. Key would be to fine tune flow rate? Not trying to reinvent wheel here ,,,,,,just thinking.:jester:

 

[Clownfish518]

If you do the UGF with no flow, you have a Jaubert system and it works very well, and a lot of papers are written on it. To oversimplify, the water in the plenum acts like a magnet and draws the water in the tank through the sand to where it goes through denitrification. I suppose you could pump water through it, but nature loves an equilibrium and you get the same effect of water movement just by having the plenum The oxygen and nitrate rich water wants to reach the anoxic plenum and dilute it, and percolates through the sand bed to reach it but never quite gets there as it gets processed along the way.

 

[Paul B]

If the idea is to create the largest LOW oxygen area possible why not the DSB with a UG and a very slow flow? In theory all sections of the DSB would receive "some" oxygen. Key would be to fine tune flow rate? Not trying to reinvent wheel here ,,,,,,just thinking.

This has been suggested numerous times and unfortunately will not work for more than a very short time. It will become a sand filter which will clog completely.
A Jaubert system which was invented by Jean Jaubert works very well and is rarely used anymore. It is also called a Plenum system. Bon Goemans wrote a book about it but I have never read it.
Bob, by the way is a hobbiest like the rest of us. He has been to my home many years ago and he is a retired arbitrator. That article was not written by him. He published in a reef newsletter what other researchers wrote so any mis information came from them.
He did put his ideas in there but the research came from others.
Back to Jaubert. He is really an oceanographer and runs the Monaco (I think) aquarium. He also took over the role of Jacque Cousteau after Cousteau passed away.
His system, like all systems works. But like all systems, it has a lifespan. The lifespan is determined by sand depth and particle size along with other factors like feeding schedules and a host of other variables.
Today the Jaubert system is the forerunner of the DSB and most people have ababdoned the plenum. I don't think there is any difference in using a plenum or not.

 

[fishkisser]

can crushed coral 1-5 mm be used in a plenum system and why is "gravel' recommended?

 

[Paul B]

CC can certainly be used in a plenum but I doubt it would do anything for nutrient removal. Gravel is only recommended by me as far as I can tell.
I don't run a plenum or DSB.