Dsb's work, what makes them work best?

[Acipenser]

Bertoni - my appologies!!

Bertoni - my appologies!!

Bertoni,

I am sorry. I creditted the quote to the wrong individual. I should have written barryhc.

quote:
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Originally posted by Acipenser
Bertoni,

Care to elaborate? PM me if necessary.

Seems to me that they have a lot of information on the subject and to flatly reject their ideas seems a little irresponsible for this thread.
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Sorry for the confusion.


__________________

 

[joefish]

As much as I like Anthony , I don't agree with the DSB bucket thought .

Now if I'm getting this right , a DSB only process what falls on it . This being it's not used like a mechanical filter and water doesn't actualy pass through it .

So why would you use a bucket to collect detritus and process it instead of just mechanicaly filtering it or siphoning it out ?

This has bugged me since the first time I've heard it . Since Po4 is realeased during the N cycle it's almost counter productive .

 

[kbmdale]

<a href=showthread.php?s=&postid=6476586#post6476586 target=_blank>Originally posted</a> by joefish
As much as I like Anthony , I don't agree with the DSB bucket thought .

Now if I'm getting this right , a DSB only process what falls on it .

I don't think that is right, the problem is it doesn't process the large stuff that falls on it. Its a biological filter not a mechanical one. The fauna and microfauna consume some of what falls on it but not in a grand enough scale to be effective..

 

[barryhc]

<a href=showthread.php?s=&postid=6476490#post6476490 target=_blank>Originally posted</a> by onthefly
Well plenty of people have done it....and in my case, no "big mistakes" were made. My only guess was the lack of sand movement and high flow (75x). Since the only section that was solid was the section in the highest flow. I had plenty critters, but lacked nassaraius snails or some other type of sand "mover".

This sounds a bit strange ( the high flow ), but what particle size were you using? Those sand movers are a BIG plus. Maybe the critters you had didn't like the flow, and stayed in lower flow areas. Nassarius snails are excellent "movers" along with cucumbers.

For those interested in silica based sands......the major contaminating compound is feldspar (like weatherman posted). Get an MSDS on the composition of the sand and make sure it isn't there. I've built 2 silica based tanks with "quikrete medium grade commercial sand" from Lowes ($6 for 100lbs). Ivory white, southdown size grains, and the MSDS says 99.9% silica sand.

What are "southdown grain sizes", and was this the material that got hard? Istill don't like the "mud" stuff, and I'm going to keep it out of my tank until its use is justified.

> barryhc

 

[npaden]

<a href=showthread.php?s=&postid=6476199#post6476199 target=_blank>Originally posted</a> by alten78
What I was waiting to read through all this was the actual day to day, weekly, or monthly maintenance and husbandry by those who havent had "problems" and those that have. The only thing I saw (unless I missed it) was not to stir it up or vacuum?

I think something that has been mentioned by a few of us is that there isn't a magical bullet. The amount of stuff you take out of your tank needs to equal or exceed what you put into your tank. It doesn't matter if it is a BB, SSB or DSB. I've seen people do this through siphoning detritus, vaccumming shallow sandbeds, macro algae refugiums, even through a xenia refugium. And another thing that I think is important regardless of your substrate choice is excellent water flow and a very good skimmer.

One thing that I think I've noticed from this thread is that it is VERY difficult to point out even 1 or 2 items that are going to make the difference between a successful DSB tank vs. an unsuccessful one. I don't really see anything that joefish did to cause his to fail but it seems that once he switched to BB he didn't have any additional nutrient problems. I'm by no means a perfectionist who did everything right but my tank seems to be running like a champ 4 1/2 years. I don't have an explanation for that.

FWIW, Nathan

 

[joefish]

<a href=showthread.php?s=&postid=6476635#post6476635 target=_blank>Originally posted</a> by kbmdale
I don't think that is right, the problem is it doesn't process the large stuff that falls on it. Its a biological filter not a mechanical one. The fauna and microfauna consume some of what falls on it but not in a grand enough scale to be effective..

Yes , but water doesn't flow through the sand . So how does it lower NO3 then?

 

[Weatherman]

<a href=showthread.php?s=&postid=6476586#post6476586 target=_blank>Originally posted</a> by joefish
As much as I like Anthony , I don't agree with the DSB bucket thought .

Now if I'm getting this right , a DSB only process what falls on it . This being it's not used like a mechanical filter and water doesn't actualy pass through it .

So why would you use a bucket to collect detritus and process it instead of just mechanicaly filtering it or siphoning it out ?

This has bugged me since the first time I've heard it . Since Po4 is realeased during the N cycle it's almost counter productive .

I think the theory is that the DSB in a bucket will process any nitrate that has entered the water through diffusion.

But, as you mention, the problem with the theory is that nitrate is simply an electron receptor for the decomposition of organic matter (which may contain phosphate). The organic matter has to get into the sand bed also, and once there, there is no phosphate export mechanism.

 

[Acipenser]

Definitions!

Definitions!

I think we need to clear up a few things. People are using a few words incorrectly which may be leading to some confusion.

nitrification- the reduction of ammonia to nitrate by nitrosomonas and nitrobacter bacteria. (requires oxygen)

denitrification - the removal of nitrogen compounds by the conversion of nitrate to nitrogen gas. (does not require oxygen)

Also there seems to be a little confusion on the use of the words nutrients. Strictly speaking they are not being used incorrectly, but I think we could clear things up by using more desciptive terms. People are using nutrients to refer to particulate matter (poop, detritus, etc..) and to dissolved organic compounds (DOC)(ammonia, nitrite, nitrate, etc..). We need to have a clear understanding of what is referred to. This different compounds are taken care of in different ways.

For instance:

First, two comments on the bucket method
1) Getting nutrients from the tank to the bucket could be very difficult. However, good turnover and a little engineering should circumvent that aspect.

The nutrients that Calfo was referring to are Nitrates. They will be carried to the bucket through the water supply. Particulate matter is supposed to pass through the bucket or collect prior to entry by mechanicla filtration and not to be processed in the bucket.

Diffusion is worthless to move nutrients in and out of the sandbed because it's far too slow.

Here Bertoni is referring to dissolved organic compounds which will diffuse from an area of high concentration to an area of low concentration, no matter what we do.

We need to have a clear understanding of what others are referring to in order to make a good discussion.

 

[kbmdale]

<a href=showthread.php?s=&postid=6476709#post6476709 target=_blank>Originally posted</a> by joefish
Yes , but water doesn't flow through the sand . So how does it lower NO3 then?

ACTUALLY IT DOES... The part I think your not getting is the biological attraction between 2 chemical compounds or the splitting there of... The sand bed particles attract water column particles.

LOL..thats lamons terms..heck I'm not a PHD..Bertoni could explain it better.

 

[inwall75]

Onthefly,

I'm sorry that my "onthefly" comment was not thoroughly thought through. I've not had a problem but there are numerous reasons why that could be.

Joefish,

Even if waste doesn't fall on the DSB, it will rot and will produce ammonia. Then you don't have control over it. If the ammonia is in the water from waste that rotted elsewhere, the bacteria still want to engage in ETS. This ammonia will go through the water column and proximity really isn't an issue to them.

 

[tsquad]

<a href=showthread.php?s=&postid=6476490#post6476490 target=_blank>Originally posted</a> by onthefly
Well plenty of people have done it....and in my case, no "big mistakes" were made. My only guess was the lack of sand movement and high flow (75x). Since the only section that was solid was the section in the highest flow. I had plenty critters, but lacked nassaraius snails or some other type of sand "mover".

For those interested in silica based sands......the major contaminating compound is feldspar (like weatherman posted). Get an MSDS on the composition of the sand and make sure it isn't there. I've built 2 silica based tanks with "quikrete medium grade commercial sand" from Lowes ($6 for 100lbs). Ivory white, southdown size grains, and the MSDS says 99.9% silica sand.

An aragonite sand bed (CaCO3) will turn into a brick for one (or both) of these two reasons:

1. You have pH swings. Lower pH (at night/morning) will dissolve some of the CaCO3, and then later that day/evening, when the pH has risen again, the sand that dissolved will solidify again. Over time, the entire bed will just become a rock. Similar to a snowbank...first you have snow. It melts, then refreezes that night. After a week or so, you have a solid block of ice.

2. Your grain sizes are irregular. Jagged and crystalline (a lot of SiO2 sands are like this, partly causing the myth of silica sand being bad; it's obviously not due to it's chemical composition, as the sand is the exact same thing as the glass, just the glass is amorphous) grains have a tendency to compact, causing the bed to solidify.

 

[barryhc]

<a href=showthread.php?s=&postid=6476456#post6476456 target=_blank>Originally posted</a> by joefish
When I use the term failed DSB , it means I kept upgrading my husbandry skills with no avail .

If your husbandry skills were being upgraded significantly enough to mention it here, then maybe it was too late, or not enough algae eaters, or not enough sand "stirrers", or . . . .

Again if stony corals are being kept , the sight of most algaes should be used as a sign to correct something .

Like critter populations, or "mud" in your filter.

Reef tanks are not defined as SPS dominated. Many SPS are touchy about nutrients, and many are not as much so. Many long term DSB tanks have healthy populations of all types of SPS.

> barryhc

 

[inwall75]

Good Heavens....I wish the phone would stop ringing.

After reading what I missed because of the phone call and my typing, I realized that I needed to point out that ETS is Electron Transport System.

 

[joefish]

<a href=showthread.php?s=&postid=6476744#post6476744 target=_blank>Originally posted</a> by Weatherman
I think the theory is that the DSB in a bucket will process any nitrate that has entered the water through diffusion.

But, as you mention, the problem with the theory is that nitrate is simply an electron receptor for the decomposition of organic matter (which may contain phosphate). The organic matter has to get into the sand bed also, and once there, there is no phosphate export mechanism.

Now I'm totaly impressed with you . You can take my jiberish and make it sound smart .:lol:

 

[barryhc]

<a href=showthread.php?s=&postid=6476096#post6476096 target=_blank>Originally posted</a> by bertoni
Diffusion is worthless to move nutrients in and out of the sandbed because it's far too slow. Sandbeds do get some bulk flow that should help some, but without animals, the sandbed isn't going to function the same way. No processing of solid wastes as desired, etc.

"Worthless" is a HUGE word.

Sand beds get a lot more Advection ( bulk ) floe when they have a layer of .5 to 1.5mm sand at the top, and with the much larger flow that this allows.

I sure do like the animals, I'm going to keep them in my tank.

> barryhc

 

[inwall75]

<a href=showthread.php?s=&postid=6476824#post6476824 target=_blank>Originally posted</a> by barryhc
Sand beds get a lot more Advection ( bulk ) floe when they have a layer of .5 to 1.5mm sand at the top, and with the much larger flow that this allows.

That's been my experience as well.

 

[joefish]

<a href=showthread.php?s=&postid=6476755#post6476755 target=_blank>Originally posted</a> by kbmdale
ACTUALLY IT DOES... The part I think your not getting is the biological attraction between 2 chemical compounds or the splitting there of... The sand bed particles attract water column particles.

LOL..thats lamons terms..heck I'm not a PHD..Bertoni could explain it better.

Are you saying the DSB in a bucket acts like a magnet and sucks NO3 out of the water ?

If not I'm lost .

 

[joefish]

<a href=showthread.php?s=&postid=6476763#post6476763 target=_blank>Originally posted</a> by inwall75


, the bacteria still want to engage in ETS. This ammonia will go through the water column and proximity really isn't an issue to them.

This is where you lost me .

The DSB is just a breading ground for bacteria that is free floating .

Or is it bacteria sits on the surface and grabs the flowby no3 out of the water ?

 

[inwall75]

There are bacteria that are motile and run around in the water column. However, they are the rarity compared to most bacteria that are living in biofilms everywhere else.

If water is passing by a bacterium that contains ammonia or Nitrite, then they want to process whatever hits them. Not all of these bacteria are in a sandbed. Some are in LR and some are on the walls of your aquarium, etc. Electron exchange happens pretty quickly and is actually not done on purpose...it's strictly chemical.

EDIT: Here's a great read. http://www.sp.uconn.edu/~terry/Common/respiration.html

 

[Acipenser]

Diffusion!!!

Diffusion!!!

I think we all need to get a better handle on the process of diffusion.

Definition: Movement of a fluid from an area of higher concentration to an area of lower concentration. Diffusion is a result of the kinetic properties of particles of matter. The particles will mix until they are evenly distributed.

Any dissolved compound will be evenly distributed throughout the water column. When you reduce nitrates in one area (DSB), nitrate will "flow" to that area to equalize the concentration. A sand bed is no obstacle to diffusion. A semi-permeable membrane - yes, sand - no.

The point is that the organic matter does not have to get into the bed to be processed. The organic matter can be broken down anywhere by any creature. It will be converted to ammonia. Ammonia can be processed anywhere two species of bacteria can colonize (glass, pipes, live rock, sand, etc...) and oxygen is present (alkalinity must be present too, but that is another story). The nitrate will get to the lower areas of the DSB (bucket or in tank) no matter what!

I also feel that diffusion is sufficiently fast to work for denitrification in a DSB.