Plenums and the wasting "option"

[CaptiveReef]

Originally posted by barryhc
By CaptiveReef:



If we move the "entire water column" down, from the top of the water, to the glass at the bottom of the tank, and the distance we move this water is, say, 1/8", and that is 1 pint of water, and it takes about 5 seconds, and then we leave it alone for 8 hours, what is the effect going to be on the bacteria?

I have to start here. > barryhc

The area we are really concerned with is the top layer of the DSB or Plenum, that pint of water can be constantly moved from the water column to the top of the bed at a rapid rate,( the normal flow a powerhead would create), but it's the rate it goes through the bed, a 5 second draw through the bed would destroy the environment for the bacteria, the 8 hours after would not even matter with that pint of water. There has to be natural diffusion in the bed up to that eggcrate level, then a 5 second draw can be made without effecting the upper levels.

CaptiveReef

[barryhc]

Yes Kris, I read all of it. Did you notice that the thread "died" in Nov. of 2004?

Everyone got "bogged down" in "detritus removal" and nothing got tried or reported on.

I can handle detritus removal at the surface pretty easily, so that thread just wasn't offering anything for me.

They never really adressed the issue of maintaining an advantageous "oxygen gradation" in the substrate, or what particle size, bed depth, flow rate, layering, frequency or volume of "draw", etc.

Oh well. > barryhc

[CaptiveReef]

Originally posted by barryhc
By CaptiveReef:



So flow through the substrate is equal to the "outflow" of the power filter?

This flow is "continuous"?

Is this affecting the oxygen level in the "substrate"?

Thanks again. > barryhc

Yes the flow is equal and continuous, I'm using the substrate as a pre-filter, there is a divider wall that has a DSB on the other side. Using a very small under rated powerfilter I'm able to create the constant draw through the substate, then directly into the skimmer then into the powerfilter, back into the tank.


CaptiveReef

[barryhc]

By haid:

I have also been thinking about some of this. What I was thinking however would be to get some flow without oxygen into the bottom plenum, thus doing your mixing. Then use a metering pump to continuously draw water from the plenum. This should stabablize any rapid changes in the bacteria levels. I was trying to come up with a good way to seperate the anoxic layer and the aerobic layer. I was thinking something along the lines of what a reverse undergravel filter would do. Use some real fine sand above the plenum (to house the aneroxic) then have a space of some sort (maybe manifold/undergravel here) then a larger grain size for the top layer. Continually wasting from the plenum and occasionally back flushing the top larger grain substrate. This should leave the aneroxic layer alone while allowing a lot of detritus to be pushed from the larger grain anerobic layer above. The skimmer could then remove what is pushed into the water column. Just what I have been thinking.

Haid, I think your starting to get into my particular area of interest here, by discussing the "oxygen levels" ( or gradations ), in the substrate.

However, I think the term "Aneroxic" is exceedingly dangerous!

Aerobic > Lots of oxygen > maybe up to 80% saturation near the substrate surface.

Anoxic > Not very much oxygen > I haven't seen any good definitions.

Anaerobic > Devoid of oxygen.

These terms, Anoxic and Anaerobic, get thrown around a lot, but it is really hard to tell, a lot of the time, what the person using the term, might actually mean by it. Seriously!

The "Goemans and Gamble" cdrom, "New Wave" makes a careful distinction of these terms, and it is an interesting read. It is "Ungodly" lengthy, and I don't necessarily subscribe to many of the Proposals made in that 'Ebook".

You might actually be making a good point here, but I have to point out the distinction of these terms, before I can consider it more seriously.

I'm hoping you might have meant "Anaerobic".

Did I get lucky? > barryhc

[barryhc]

By haid"

Continually wasting from the plenum and occasionally back flushing the top larger grain substrate.

I believe that any kind of "true continuous wasting" causes a mechanical "nightmare" for "flow balancing".

Read the thread from the beginning if you want a more thorugh explanation of flow balancing, and why "short duration draws" will keep "downflow distances" within a range, that the bacterial populations can thrive in, instead of "suffer from"!

Nice to have you here. Thanks > barryhc

[haid]

barryhc,


Yes, Anaerobic is what I meant. Sorry not always great with terminology. I would think this method would allow you to keep the top layers from going anaerobic(pushing water up and through from the column), reduce the load on the sandbed to begin with, with less large particles there to break down. The phosphate should migrate most of the time to the bottom plenum and be wasted in a slow continuous manner. In effect draining water for small but continuous water changes.

[barryhc]

Well, "haid", that's pretty interesting, actually, It is sort of the opposite of what I am trying to do, and that could be closer than people think.

I'm just going to post his now, because usually, "we" end up trying to type fast enough to keep the posts "in order ", and that often causes the posts to "cross" in transmission, and seems pretty "odd" to many of us when we read them!


Thanks again. > barryhc

[barryhc]

By CaptiveReef:

The area we are really concerned with is the top layer of the DSB or Plenum, that pint of water can be constantly moved from the water column to the top of the bed at a rapid rate,( the normal flow a powerhead would create), but it's the rate it goes through the bed, a 5 second draw through the bed would destroy the environment for the bacteria, the 8 hours after would not even matter with that pint of water. There has to be natural diffusion in the bed up to that eggcrate level, then a 5 second draw can be made without effecting the upper levels.

Why is it the "top layer" that we are concerned with, and just how deep is this top layer?

The 5 second "draw" is a "sub function" of "draw depth". It is not the important factor here.

The "draw depth" is the important factor, at least in my opinion, and it is of course, only an opinion, but we could make the "duration" of the "draw" 1/2 second if you like, or 30 seconds, but it is the depth of this draw, that will most affect the bacteria.

"Draw depth" is the distance you "pull" water down into the substrate each time you "draw" through the plenum.

If this "depth" is that crucial, we could reduce that depth to, say, 1/32" each time.

You are headed in a slightly different direction here, than I am,
and I don't have any problem with that, but I don't think the bacteria really care.

If the bacteria population is going to be destroyed by drawing water into the substrate 1/8 " at a time, then I would like to hear some explanation as to why, or how, that is so.

I'm not even disputing it, yet.

Thanks again, > barryhc

[barryhc]

By "haid":

Yes, Anaerobic is what I meant. Sorry not always great with terminology. I would think this method would allow you to keep the top layers from going anaerobic(pushing water up and through from the column), reduce the load on the sandbed to begin with, with less large particles there to break down. The phosphate should migrate most of the time to the bottom plenum and be wasted in a slow continuous manner. In effect draining water for small but continuous water changes.

Well, I agree with most of this actually, if I'm reading it right.

I don't think though, that we have any concern, or problem, so much, with the "upper level" ( or layer ) "going Anaerobic", but how deep, or thick, is this "upper layer" anyway?

Especially, if "we" are "forcing" water to flow down into the substrate very often, for very "short distances"? This will keep the "upper layer" Aerobic, right?

I do not believe that this would over "oxygenate" the "depths" of a 6"- 8" deep substrate. This would be at the rate of about 5/16" of downflow, per day. It would take 20 days for this water to reach the top of the plenum. This rate, is going to destroy the bacteria?

I am actually looking for "critters", crabs in particular, to keep the surface of the substrate rather clean, and high flow, as well, to keep this "stuff" in "suspension", for removal by skimming etc..

Substrate in the 1-2mm range will "reject" a very large portion of any detritus that "wants" to collect at the surface, and crabs, and high flow, would get "it" into the water column.

This portion of the detritus control consideration is working very well, in my tank, and has been for more than 7 mos.. I know that isn't all that long, but I would have noticed a detritus problem by now, wouldn't I?

Anything "continous" has a lot of associated "flow balancing" problems, if the flow is going to be "wasted".

Let me know what you think here "haid", and Thanks. > barryhc

[CaptiveReef]

Originally posted by barryhc
By CaptiveReef:


Why is it the "top layer" that we are concerned with, and just how deep is this top layer?

The 5 second "draw" is a "sub function" of "draw depth". It is not the important factor here.

The "draw depth" is the important factor, at least in my opinion, and it is of course, only an opinion, but we could make the "duration" of the "draw" 1/2 second if you like, or 30 seconds, but it is the depth of this draw, that will most affect the bacteria.

"Draw depth" is the distance you "pull" water down into the substrate each time you "draw" through the plenum.

If this "depth" is that crucial, we could reduce that depth to, say, 1/32" each time.

You are headed in a slightly different direction here, than I am,
and I don't have any problem with that, but I don't think the bacteria really care.

If the bacteria population is going to be destroyed by drawing water into the substrate 1/8 " at a time, then I would like to hear some explanation as to why, or how, that is so.

I'm not even disputing it, yet.

Thanks again, > barryhc

In this theory the upper layer of substrate is the deeper portion of this bed. The bottom layer is sharing space with the manifold most of the draw point will be around the manifold and just above it. With the 5 second draw these low area's will be only affected, the upper depth of the bed will not be affected so oxygen will not be pulled into the bed.
This way diffusion will be performed naturally in the upper bed, and the waste that has been diffused down to the manifold area can be drawn out.
You are looking to manually draw the water 1/8 inch at a time through the bed, you would have to draw the water from an uplift tube, like you said a pint at a time every 8 hours.
The only problem I see with this is 8hrs enough time for the bacteria to break down the Nitrate into Nitrogen before the next draw.
You are going to have to build a prototype and try it, if you have a rise in Nitrates then the process is compromising the DSB.


CaptiveReef

[kbmdale]

so basically Now we have come to the conclusion that there are 3 layers in the substrate we should be concerned with. The upper aerobic, the middle anoxic, and the bottom anaerobic....

So If we draw to much we would effectively hender the anoxic because it would be the first area to be introduced to 02....Well there is another variable to be considered.

All three layers are important correct? Is there any reading of info on the precise function and what is broken down in these three layers?

[barryhc]

By CaptiveReef:

In this theory the upper layer of substrate is the deeper portion of this bed. The bottom layer is sharing space with the manifold most of the draw point will be around the manifold and just above it. With the 5 second draw these low area's will be only affected, the upper depth of the bed will not be affected so oxygen will not be pulled into the bed.
This way diffusion will be performed naturally in the upper bed, and the waste that has been diffused down to the manifold area can be drawn out.

>>Well, "kinda-sorta", I guess. I can't tell if this is your theory, or my theory. It sounds like a combination of both to me.

By CaptiveReef:

You are looking to manually draw the water 1/8 inch at a time through the bed, you would have to draw the water from an uplift tube, like you said a pint at a time every 8 hours.

>>Yes.

By CaptiveReef:

The only problem I see with this is 8hrs enough time for the bacteria to break down the Nitrate into Nitrogen before the next draw.

>>H-m-m-m, If we "draw down" the "entire water column" by .001", and do this 375 times a day, once every 3.8 minutes, then we will move the "entire water column" down by .375" a day. > 3/8" right?

This is going to cause an "oxygen gradiation" to occur within "the entire depth of the substrate". right?

This is going to mean Aerobic conditions at the surface of the substrate, and then "gradually" reducing amounts if oxygen is "we" go deeper into the substrate. right?

The Aerobic area in the substrate will extend farther down into the substrate than it does in "conventional" DSBs or Plenums. I'm not sure how far.

The Anoxic area in the substrate ( which is particularly "thin" in DSBs ) will become stretched ( thicker ), and also extend farther down into the substrate than it does in "conventional" DSBs. Again I'm not sure how much ( thickness ), or how far ( depth ).

The Anaerobic area in the substrate will of course come now, below the Anoxic area, and will extend down to the glass.

This represents an "oxygen gradient" in the substrate

It is my intention to have the plenum "drawing" small volumes of water from this Anaerobic area at the bottom very frequently. That is however frequently is necessary to avoid causing any "undue harm" to the bacteria populations.

If "we" had an oxygen probe at 2" or 3" inches above the plenum, I predict that very, "VERY" little fluctuation in the oxygen "level" would be noted.
< bhc >

By CaptiveReef:

You are going to have to build a prototype and try it, if you have a rise in Nitrates then the process is compromising the DSB.

I installed the prototype 4 mos. ago, and I have not started wasting yet. My Nitrates are < 1ppm currently. When I ( or anyone else ) start "wasting", I think several components in the effluent should be checked.

Oxygen for one, of course!

Phosphate as well, I think.

Nitrates? I think I'll just keep an eye on the tank water, like you say.

I hope this clears things up a "tad bit". I'm just trying to help.

Now about diffusion. Just what does "diffusion" mean anyway? Any thoughts on this, by anyone?

Thanks, Captive reef, and "all"! > barryhc

[barryhc]

Kris, You posted while I was typing my reply. It's hilarious sometimes, isn't it?

I agree with you post immediately above! > barryhc

[kbmdale]

As far as importance and proccess,

I think the top layers have the greatest job doing the nitrification

the byproduct of that is proccessed further in the second axonic layer

then anything left over is proccessed and stored in the bottom (sink)...

If this is correct, we should be able to move anything we want out of the sink without hendering the tanks biological filtration being doen in the SUBSTRATE....TRUE

If we remove the "sinks" collection of byproducts to fast we will force the 2 areas above to loose effieciece by shrinking the axonic area. If we remove it to slow, we will still allow for a build up which in itself will reduce the anoxic area by having the anaerbic area grow in that way....


MAN we really really have to find the right equation for "waste amount" "Pull duration"....If its wrong we could just be making things worse...


I'm not being Negative, But I am just now seeing the area that will be effected by to little or to much pull, and the bacteria in that area would be the first to suffer. If there were a way to monitor that axonic area of the bed this puppy could be dialed in to perfection....AGREED?????? or am I Just a nutty guy running on to little sleep...

[barryhc]

So, exactly Kris, let's find some of that reading. Randy Holmes Farley, might have some, Eric Borneman R. Shimek maybe, and many others.

The above three might be more toward DSBs, and that's perfectly fine. We needn't endorse "everything" that anybody else says in "it's entirety", either, but reading is good!

This is where I've been trying to go for 3 pages now, I'm very patient.

There is going to be an "oxygen gradation" in the particular system that I am "currently" promoting, and for that system, we have to allow that "bacterial process depths", are not going to coincide exactly with any published information.

In fact, for my case, I don't want them to "conform", I wan't to improve them. Particle size, bed depth, "draw depth and frequency . . . there I go again!

Let,s find some of this good reading, and maybe define "diffusion" while we're at it.

Thanks again Kris! > barryhc

[barryhc]

We're "passing in the night again" Kris. Right again!

E X A C T A M U N D O !!!!!!!!!

> barryhc

[barryhc]

Kris, I believe that the Anoxic zone is going to stretch ( get thicker ), and the anaerobic zone will become "somewhat thinner".

"We" need to cause the thickness of the anaerobic zone, to become thinner, but not "gone", thus maintaining, and actually "improving" the thickness of the Anoxic zone. I have been trying to get anyone in the world to understand this for over three mos. now.

It seems like you do! and Thanks again! > barryhc

[kbmdale]

Well I understand that I think thats working in a posative way... As long as that axonic area doesn't shrink I don't think the bacteria will be hindered.

So by it growing downward (baby steps) it should make for more effeiciency...RIGHT ON BARRY

[barryhc]

We just love that anoxic zone don't we? Let' stretch it a "bit".

Actually when you find some reading on this, "Many" will say that the Anoxic zone only exists for maybe as little as .5mm in a DSB.
I can't say that "it's" true, but you will read it!

You may also read, that the Aerobic zone, exists for only 10mm or so, that would be without the help of "critters" of course, and almost nobody does that, and "cukes", "Nasarrius snails", etc.. will very significantly effect this "depth".

"Depth", I say? What depth ? Diffusion depth? Just what is "diffusion" anyway? Ever hear of "advection"? "Goemans and Gamble" talk abou it, and I under stand it, but I don't ever see it in common use.

Advection depth for us here, is that depth of "pore-water"
flow, that occurs as a function of the flow in the water column.
That would be for us, not from wasting, or bacteria, or from critters, just from water column flow interacting with the particle size in the substrate.

Almost no advection occurs in a "sand bed" ( like typical DSB ) because of the grain size. Some advection occurs in "standard plenums" because of the larger particle size, 2-4mm is common.

So, what is "diffusion"? Thanks > barryhc

[kbmdale]

During his MACNA XVI presentation, Julian Sprung discussed his research into the physical effects of water motion on the biological filtration capacity of sediment beds in aquaria. The basic conclusion from that work (covered in more detail in Delbeek, Sprung, In press) is that the location and volume of rock as well as the surface shape of the sand or gravel (e.g., mounds, sloped, or flat) can dramatically affect the efficiency of water flow, oxygen diffusion and nutrient processing in the sandbed. The results we present here likewise argue that there are complex interactions between sandbed depth, particle size and flow that are sometimes counter-intuitive. Obviously, additional research along these lines may prove very fruitful to our ultimate understanding of biological filtration in recirculating aquaria.

http://www.advancedaquarist.com/2005/7/aafeature

I can't answer about diffusion YET...But this article has some really good studies on the sediment size, water flow, and depths....Could be a very useful as far as getting a few numbers and size to rate ratios...

NOw I'm on to diffuse diffusion...

I'll be back later after a doctor visit...

[barryhc]

I heard a couple months ago, that Julian was going to present some information that sounded like what I was looking for.

I didn't know that it had become available.

I'm off to read, but I will still be here. Thanks > barryhc

[barryhc]

Kris, I did a very quick "skim" on the link that you gave me, and I think I'm already up to date on that.

I don't think that "they" are playing around with "wasting" yet, so "we" have to be careful what we read into any conclusion that "they" come to.

I think it will remain an "important read", let's just be careful about our own conclusions. I like the fact that they are going to include more animals now, I happen to be generally in favor of them, and it is the "whole system", that works or not including "blah- blah-blah" I won't start on that again right now!

Thanks > barryhc

[barryhc]

I think another very important "read" for us here is the "BRP" thread I mentioned previously. All kinds of information there regarding Aerobic to Anaerobic and back again, and how this is being used to process Phosphate primarily.

It may not seem to represent what were trying to do here, but, if the downward flow was 5/8" every other day, what would be happening to the bacteria? I'm not promoting anything like this "currently", but it is educational just the same, regarding "draw depth" and "frequency", heh?

I haven't yet found anything else that seems to be "real close" for us. Actually, I think "we" are the ones who are on the leading edge of this! That "we", is "everyone" who is posting in this thread!

Thanks all. > barryhc

ooPS! another "ringy-dingy" 4 seconds ago!

[CaptiveReef]

Well I'll try to tackle the ol diffusion discussion without making a fool out of myself, (I hope).
As we know diffusion occurs in the DSB where the perfect conditions are present to create an anoxic zone.
The actual diffusion is when the bacteria in the anoxic zone use the NO3 to breathe they strip away the oxygen molecule and leave one Nitrogen atom to bubble up as Nitrogen gas. The process of the slow release of Nitrogen bubbles and the introduction of new water into the bed when the Nitrogen is released is the diffusion process.
Hope I got this one?

CaptiveReef

[kbmdale]

I think your right on captive. Thats what I am finding in my search for he answer. So would creating a bigger anoxic area for diffusion be benifitial to the tank?