Plenums and the wasting "option"

["Umm fish?"]

How long is eventually?

No real clue, but the consensus seems to be 4-5 years, if the sand bed fails at all.

Firstly, I am lazy, and I hate water changes. I am absolutely dead serious here. Frequent Wasting will cause a "continuous water change" to occur automaticaly, and forever. For me that is a very nice feature. "Continuous water changes" are 74% as effecient as monthly water changes of the same monthly volume, and that is good enough for me. At the 1 pint per day for my system, that is equivalent to a 17% water change monthly. I highly prefer this continuous condition to "all at once" water changing.

Me, too. I putting overflow drains on my sump. So, a water change is turning off the auto top-up and turning a valve. The WC water displaces old water out of the sump. I stole that idea out of Calfo's book.

I like the idea of stretching the bacterial populations. That's good.

>>>Thirdly, this process will be "effectively continuous", which eliminates concerns about "what happened when I wasted the plenun". There is no "when I wasted the plenum", because I am "always wasting the plenum".

Right, but what if the bacteria population needs recovery time? I have no idea, personally. Time will tell, I guess.

Are you going to run an O2 or pH probe down into the bed to check O2 levels? Or do I remember a discussion about this earlier. It all gets a bit fuzzy.... :rolleye1:


Cheers!

Andy

 

[barryhc]

Barry, how far have you considered the possibility of biofilms that coat every available surface area in the tank, i,e the entire cycle occurs within a microns layer on every availabe surface regardless of the presence of 'sediment zones'

here's a random sulphur based extract that demonstrates the concept, there are millions of accredited marine biofilm articles out there.

http://aem.asm.org/cgi/content/full/65/11/5107

Within a "microns layer", what is that?

This is from reading in the link that you supplied:

FIG. 1. A cross section made with a cryomicrotome (20 Ã"šÃ‚µm thick) of an aerobic domestic wastewater biofilm. The biofilm thickness is approximately 1,000 Ã"šÃ‚µm. ( 1000 microns )

That is 1mm thick, which is .039". This is a bit thicker than 1/32".

1mm is the thickness that I stated previously regarding the "low oxygen" zone. This value is considered to be valid, in "oolitic" sand, and would be considerably thicker in a larger particle size of substrate.

I do not have any visible bio-films in my tank that are thick enough to see. This may be because of the brittle stars, and snail and crab populations. I get an exceedingly thin film on the glass after about 2 weeks, but since I clean the glass weekly . . . .

My live rock has coraline and feather dusters, and otherwise looks like "cooked rock". Same condition for 6 months. I don't stir, I don't vacuum, I don't siphon. I have proper aquascaping, 25 x flow, and skimming.

i.e. do you accept that biofilms coat every surface and in themselves are capable of completing the full nitrogen/sulfur//phosphate/e.t.c cycle at the micron level?

No, not at the "micron level". I deal in "tenths of a thousandth" everyday, which translates to 2.5 Ã"šÃ‚µm. I am INTIMATELY FAMILIAR with these "distances". One of your hairs is 90 microns thick, OK?

Isn't all that remains a method of gettind the most detritus out of system before it has chance to cycle in the biofilms??

No, detritus does not just cycle in the "bio-films', it creates them.
Don't allow detritus to collect in your system, REGARDLESS OF "BOTTOM TREATMENT"!!!!!!!!!

Read the first post in this thread, right on page 1 of coursre. This thread is for those who WANT TO RUN SUBSTRATE IN THEIR SYSTEM FOR WHATEVER REASON ! ! ! ! ! ! ! ! ! ! ! ! ! !

I don't mind that much if you are happy with BB. They are fine in very many cases, however, PLEASE read all of page 1, and the last two pages of this thread, if you expect to offer meaningful comments.

> barryhc :strooper: :hammer: :beachbum:

 

["Umm fish?"]

I'm sorry, but I must take us a little off-topic (and we are trying to avoid that).

I don't understand why BB tank people use live rock. So many make the argument that sand beds are mysteries and therefore they don't want them in the tank. Isn't the live rock a mystery, too? Wouldn't bare egg crate shelves serve the philosophy a bit better?

Okay, rant off. No more.

 

[reefclown]

Barry,
firstly my apologies for not having read the thread, having now read it I can see why your response is somewhat hostile.

No, not at the "micron level". I deal in "tenths of a thousandth" everyday, which translates to 2.5 Ã"šÃ‚µm. I am INTIMATELY FAMILIAR with these "distances". One of your hairs is 90 microns thick, OK

Barry, I'm not questioning your familiarity with distances!

In the context of this tread my last statement was insenstive/unconstructive as was any implied reference to BB, please disregard.

OK, hopefully misunderstanding cleared up and we are on a CLEAN SLATE.
----------------------------------------------------------------------------------
Now, let me attempt to rephrase what I was meaning to ask.

The thread appears to be evaluating a method of controlling bacterial activity within a sediment layer. And the core of the discussion looks at the effects of bacterial activity within that sediment under varying circumstances.

I was simply meaning to ask what activity you believe occurs at a smaller scale, for example on the bacterial film that coats a single grain of sand. Is this bacterial film capable of completing the full nitrogen cycle. i.e does the bacterial film covering the grain of sand contain aerobic, anoxic and anaerobic zones/bacteria within it?

I'm simply asking you to consider a lower denominator, as it may aid in the understanding of how the sediment will operate when the oxygen gradient changes.


from the link provided

O2 consumption took place in the upper 50 to 100 mm of the biofilm, with a rate of 0.81 6 0.13 mmol z cm22 z h21. The production of NO3 2 plus NO2 2 appeared in the same layers....
Denitrification in the layers below 150 mm ranged from 0 to 0.28 mmol z cm22 z h21, with an average of 0.11 mmol z cm22 z

in a reduced oxygen variant of the experiment (I thought you may have found this interesting as you are looking to determine the effects when changing the oxygen gradient in the sediment bed).

Incubation with reduced O2 concentration (115 mM) decreased both O2 penetration and metabolic rates.The O2 concentration reached levels of less than 20 mM on the biofilm surface and zero within 25 to 75 mm of depth. The total oxygen uptake was 0.35 6 0.07 mmol z cm22 z h21, whereas the production of NO3 2 plus NO2 2 decreased to 0.28 6 0.14 mol z cm22 z h21 (averages and 95% confidence limits for 10 different profiles, respectively). The main activity of nitrification was found at a depth of approximately 20 to 50 mm, and denitrification occurred in the deeper layers (100 to 200 mm), with an average rate of 0.10 mmol z

so in effect rather than the 1000 microns you mentioned earlier a more realistic target figure MAY be in the range 10-300 microns ? everything below 300 microns being anaerobic. Add degradable organic matter to the above equation and the nitrifying layer will reduce yet further?

The "low oxygen" zone comes below this where most processing of Nitrite to Nitrate occurs, and it is generally regarded to be only about .5 to 1mm thick. This is where "non-obligate-Anaerobic-faculative- bacteria" do Nitrate "processing. This is generally accepted fact by many "authorities" on the subject, and if it does not "sit well" with anyone, then this is where the bacterialogical discussion needs to continue!

I hope this goes someway to explaining why the above does not still well, and hopefully open up the discussion in the areas you intended.


peace:bum:

 

[barryhc]

No real clue, but the consensus seems to be 4-5 years, if the sand bed fails at all.

All right, that seems to be what I find as well, including the "if at all". Plenums have failed, DSBs have failed, BB systems have failed. So what. I want the sand and gravel so that the critters can live in it. I am trying to get good reliability out of it primarily, along with some processing, whatever "we" can get "reliably".

But I require it for the critters, not for "processing". I am going to have sand and gravel in my tank, FOR THE CRITTERS period!

I like the idea of stretching the bacterial populations. That's good.

A-h-h-h . . . you're getting the "stretch idea", fantastic! I must not have presnted much of this as well as I could have, because Ihave been viewing this on the basis of a "continuous-stretch" of the bacterial populations since Dec. of 2004, a long time before I started this thread.

Right, but what if the bacteria population needs recovery time? I have no idea, personally. Time will tell, I guess.

The bacteria are going to be affected by drawing water from the plenum. Water treatment facilities are getting very good at this( although some of them argue as much as reefers :lol: :lol: ). A very new "process" uses only one "vessel" and cycles between aerobic and anaerobic only ( or so they think ), which is very close to "draw water" then "wait", "draw water" then "wait".

This is in fresh water, not salt water, and they are not "exactly" the same, but . . . . . Time will tell, I'm sure!

Are you going to run an O2 or pH probe down into the bed to check O2 levels?

I would like to run O2 and/or pH probes, but my understanding is that these probes only last so long before needing cleaning and or replacement, and "servicing" the probe, would disturb the environment were trying to monitor.

I need to find out more on this. I had intended to monitor O2 and Phosphate in the effluent, and the P is still relevant to monitor here, but oxygen may change as it travels through the plenum piping and could be changed considerably if it takes two days for plenum water to actually exit the end of the plenum piping. This might be the case depending on the volume of the plenum piping, even while the "draw"remains "high flow" and "short duration" ( like 5 seconds).

You know, as I'm writing this, I'm wondering about a DIY "water extractor", that would at least let us get a representative "sample" of the water, to test "outside" of the tank, as usual. It could be made from 1/4" I.D. PVC by 1" long, capped, and plumbed with 1/8" I.D. tubing, then run outside of the tank. This would be constructed like a little "micro plenum". Several of these, say, one for every inch of substrate depth, could be installed, along with the plenum, and drawn from, before and after "wasting" to monitor various parameters, and fluctuations.

Please don't get me wrong here, "Fish" or anyone else. I still believe that several versions of this "wasting" idea, might be found to work well, and I'm not really opposed to other versions, but I still find the "High Frequency" type to fit my expectations thus far into the investigation. If I run into a hitch, especially with Bacteria, I'll run from it like a forest fire, but that is not what I have been finding.

"Fish", what think ye, of the "micro plenum water sampler"?

> barryhc :beachbum:

 

[barryhc]

OK, hopefully misunderstanding cleared up and we are on a CLEAN SLATE.
----------------------------------------------------------------------------------

so in effect rather than the 1000 microns you mentioned earlier a more realistic target figure MAY be in the range 10-300 microns ? everything below 300 microns being anaerobic. Add degradable organic matter to the above equation and the nitrifying layer will reduce yet further?

I hope this goes someway to explaining why the above does not still well, and hopefully open up the discussion in the areas you intended.

Thanks for the reply, ReefClown, you are quite gracious. I think that these processes are actually occuring at both ends of this spectrum, but it is where they "predominate" that I have been putting emphasis on. You can tell now, that I have been more interested in bacteria than anything else, since the thread started. The mechanics, just aren't that difficult.

All questions need to be answered, just the same. I hope everyone understands that I DO NOT KNOW IT ALL HERE!!!

I will know enough by Christmas, when my 200-300 gal. tank goes in.

ReefClown, our replies have "passed during typing". This happens fairly often. Consider my last post, I wrote it before I saw "your last", so it is not "in response". I am a slow typer.

I have to leave right now, not enough time to really respond, I will read, consider, evaluate and respond, possibly by tommorow.

Thanks for joining us here, learning is the goal.

> barryhc :beachbum:

 

["Umm fish?"]

Hey! I finished roughing out my grid tonight! :rollface: Now I just need to put my drill press together that showed up today and make some holes!

You gotta love Amazon. A 95 lb. drill press. It qualified for free shipping because of the price and they lived up to it. Delivery to my porch, absolutely free!

I would like to run O2 and/or pH probes, but my understanding is that these probes only last so long before needing cleaning and or replacement, and "servicing" the probe, would disturb the environment were trying to monitor.

What do you think about running a piece of pvc with ID large enough to hold the probe down through the sand layer; holes for water flow only at the bottom (inside the bed); cap on top with a hole drilled for the probe wire?

The probe can be taken in and out with minimal disturbance of the bed.

As for the micro plenum water sampler, I don't see what benefit you gain over just testing the waste water. I was thinking that some sort of probe might give you a idea of when you need to waste before you suck water out. If you used a controller with the probe you might be able to automate the whole thing.

Happy weekend!

 

[salty joe]

Hi Barry,
You asked a while ago if I had put a carbon cap on the collection pipe. Unfortunately, I am in the planning stages and will be there for quite some time.
The discussion on testing the effluent is interesting. Your idea of taking water from different parts of the plenum to see what happens after a draw is an excellent idea.
Am I off-base for thinking that testing for phosphate in the effluent will tell the story? I was thinking that once consistent phosphate readings were achieved, a balance had been struck and the sand bed could last indefinitely. Or am I all wet?

I also wonder if a less scientific test of the effluent would be useful. Like maybe get a vial of effluent and check it for color against a color chart. Maybe even notice if the smell is different.

Anyway, I find this thread very interesting and now I will go back to the lurking mode.
Joe

 

[reefclown]

Been thing about the 'pull' mechanism, and thought about an old reverse flow sand filter design from Frank De Graaf in the 70's that could be adapted to provide a simpler mechanism.

here's a sketch of an adaption.

It removes the need for a manifold and should allow for an even pull through the sediment bed. The pull pipe can be placed at any depth and simply tapped.

any thoughts?

 

[barryhc]

What do you think about running a piece of pvc with ID large enough to hold the probe down through the sand layer; holes for water flow only at the bottom (inside the bed); cap on top with a hole drilled for the probe wire?

The probe can be taken in and out with minimal disturbance of the bed.

As for the micro plenum water sampler, I don't see what benefit you gain over just testing the waste water. I was thinking that some sort of probe might give you a idea of when you need to waste before you suck water out. If you used a controller with the probe you might be able to automate the whole thing.

I don't think I can get good oxygen information from the waste water, and I want to monitor many parameters, at many depths and locations CHEAPLY. The "micro plenums" cold cost as little as $20 for about 28 0f them. I might actually use that many.

This idea is not for the average installation of one of these systems, but is instead, only for me to learn about what is going on for both my, and everyone's benefit.

Having one probe mounted in a fashion similar to what you propose, for the pupose of automation, may be a good idea, if we can find a probe that will last long enough, when continuously submerged.

Thanks, > barryhc :beachbum:

 

[barryhc]

Hi Barry,
You asked a while ago if I had put a carbon cap on the collection pipe. Unfortunately, I am in the planning stages and will be there for quite some time.

I was particularly enjoying the progress we were making then, on the "cheap-simple-automated-volume" control. I like the system that had developed at that point, with one caveat, for me anyway. That is that I remain somewhat adamant about "high flow", and that set-up is going to slow down to "zero", in a linear fashion, and that is a concern for me. I haven't thought about it since, to solve that problem, but it remains on my "burner".

Last I remember, we had "no-stink", and adjustable automated volume, "on the cheap" and easy.

The discussion on testing the effluent is interesting. Your idea of taking water from different parts of the plenum to see what happens after a draw is an excellent idea.
Am I off-base for thinking that testing for phosphate in the effluent will tell the story? I was thinking that once consistent phosphate readings were achieved, a balance had been struck and the sand bed could last indefinitely.

I am interested in Phosphate, pH, and oxygen primarily, the "micro plenum", or whatever we call it, lets us test for anything-anywhere-anytime, so to speak.

I am very much in the planning stages for my "big tank". You needn't "lurk" so deeply, come up for "oxygen" more often!

> barryhc :beachbum:

 

[barryhc]

Been thing about the 'pull' mechanism, and thought about an old reverse flow sand filter design from Frank De Graaf in the 70's that could be adapted to provide a simpler mechanism.

It removes the need for a manifold and should allow for an even pull through the sediment bed. The pull pipe can be placed at any depth and simply tapped.

any thoughts?

I don't see where this is very much different than an under gravel filter plate. It could be made to work with some modifications for better flow balancing. Drill holes in the bottom plate, or elsewise cause a "flow restriction" between "above and below", then cover with egg crate and screen to "disperse" the draw between the lower plate and screen. The restriction is crucial to balanced flow, and still requires high flow to "effectively balance".

Thanks all. >barryhc :beachbum:

ooPS: I haven't had time to review on bacteria, but it remains my highest interest, along now, with post installation "testing".

 

[reefclown]

Sediment composition aside, would it be fair to say that:

A plenum in it's basic mechanical sense in an undergravel filter with a broken airlift?
A wasting plenum is akin to an undergravel filter whereby the passing of water through the sediment bed is "controlled and wasted" rather than continuous and recycled ?

If

1.the screen and sediment composition is as you propose in your current design,
2.the plenum void space is also the same,

then the shown diagram simply equates to replacing the manifold with a tap, right ?

I'm trying to get my head around how adding a manifold improves the dynamics of waste extraction and can't quite grasp it at this moment. Am I missing something fundamental ?

 

["Umm fish?"]

Actually, having a plenum void space around the manifold might be the best best. There'd be no sand around the manifold to impede the draw. That said, I don't think I'll bother, for reasons stated farther up the discussion.

 

[barryhc]

Sediment composition aside, would it be fair to say that:

A plenum in it's basic mechanical sense in an undergravel filter with a broken airlift?
A wasting plenum is akin to an undergravel filter whereby the passing of water through the sediment bed is "controlled and wasted" rather than continuous and recycled ?

That is very close, in a "basic look" at the function.

If:

1.the screen and sediment composition is as you propose in your current design,
2.the plenum void space is also the same,

then the shown diagram simply equates to replacing the manifold with a tap, right ?

Yes, the diagram replaces the manifold with a tap, and that does not represent a problem in itself, BUT, it is not that SIMPLE.

I'm trying to get my head around how adding a manifold improves the dynamics of waste extraction and can't quite grasp it at this moment. Am I missing something fundamental ?

Yes, It is not the manifold itself that is important here, it is that the manifold was designed with a "restriction" that is created by the total area of the holes, relative to the area of the plenum piping I.D..

If you will review the previous post carefully, you will see that I explained how this restriction could be designed into the system that you offered, and that it could be made to work in this way.

It could possibly, even be a better design, in the end, IF restriction is utilized with high flow, and short duration, to achieve "flow balancing". Else-wise, "channeling" will occur, and "control" over the bacteria populations will be lost.

I hope this helps, I'm still trying to keep up with the bacteria discussion that got "dropped", from a few posts ago.

> barryhc :beachbum: :wavehand:

 

[barryhc]

ReefClown, I have finally gotten around to reviewing your information on "bio-film thicknesss".

The thread appears to be evaluating a method of controlling bacterial activity within a sediment layer. And the core of the discussion looks at the effects of bacterial activity within that sediment under varying circumstances.

I was simply meaning to ask what activity you believe occurs at a smaller scale, for example on the bacterial film that coats a single grain of sand. Is this bacterial film capable of completing the full nitrogen cycle. i.e does the bacterial film covering the grain of sand contain aerobic, anoxic and anaerobic zones/bacteria within it?

Quote, from your link:The result of microelectrode measurements showed that a high sulfate-reducing activity was found in a narrow anaerobic zone located about 150 to 300 Ã"šÃ‚µm below the biofilm surface and above which an intensive sulfide oxidation zone was found. The biogeochemical measurements showed that elemental sulfur (S0) was an important intermediate of the sulfide reoxidation in such thin wastewater biofilms (approximately 1,500 Ã"šÃ‚µm), which accounted for about 75% of the total S pool in the biofilm.?

>> 1,500 Ã"šÃ‚µm is 1.5mm which is 1/16". ( "thin wastewater bio-films" )

Quote, from your link:Therefore, successive vertical zonations of predominant respiratory processes occurring simultaneously in close proximity have been found in aerobic wastewater biofilms with a typical thickness of only a few millimeters

>> A "few millimeters" = 3mm = 1/8". ( typical thickness )

Quote, from your link:Composite DIC image of the entire biofilm vertical section (scale bar = 200 Ã"šÃ‚µm). The biofilm thickness is about 1,500 Ã"šÃ‚µm.

>> Again, 1,500 Ã"šÃ‚µm is 1.5mm which is 1/16".

I did not think that you were questioning my understanding of distances, I was questioning yours.

I'm simply asking you to consider a lower denominator, as it may aid in the understanding of how the sediment will operate when the oxygen gradient changes.

so in effect rather than the 1000 microns you mentioned earlier a more realistic target figure MAY be in the range 10-300 microns ? everything below 300 microns being anaerobic. Add degradable organic matter to the above equation and the nitrifying layer will reduce yet further?

If we can come to some agreeable understanding of various bio-film thicknesses, then we might be able to make some progress on bacterial population discussions. I am looking forward to it.

Let's start. I think that the point that is being made, about the bio-film, is that the surface of the "bio-film" is aerobic to begin with, such as would be the case, where algae on a surface, feed nutrients to the aerobic bacteria at the surface of the bio-film, which nutrients are then processed by the aerobic bacteria, into "food-stuffs" for the bacterialogical populations that are "deeper in" the bio-film.

I think that this MAY BE more predominant, in thicker bio-films, that are being fed with "solids", and less likely in "thinner populations that recieve their food from dissolved nutrients. Especially so, where these bacteria live in a "zone", that is not entirely "stagnant".

I don't believe in allowing detritus, fish poop, etc. , to collect at the substrate surface, and it does not occur in my current tank. So, I have not been looking at this system having to deal with high loads of undissolved solids, but more on the basis of dissolved nutrients, that are "common" to the water column, as a whole.

I think in terms of the "lower denominator", I have been thinking in terms of bacterial "films", if you like, that are as thin as 5 microns, or 5 Ã"šÃ‚µm, in the "Aerobic" upper layer of the substrate. I suspect that these "upper bacterial populations" would remain "thinner", because the water is not being allowed to become stagnant. This would only be true, of course, for the "High Frequency" type of plenum wasting.

I further suspect, that these "films" could become somewhat thicker, deeper in the bed, in the "Anaerobic zone" ( below 1-2" ) because "upward diffusion" is probably less predominant in this area, and is partially responsible for the "sinking" that is so commonly referred to in "DSB discussions".

How is that for a "restart" on bacterial discussion?

> barryhc :beachbum:

 

[barryhc]

Ok, for those who might "pop-in" here, and can't deal with reading the whole thread, which is getting lengthy, and for any who might have forgotten the emphasis of this endeavor, I am including an excerpt from another discussion, that offers a reasonably short summary, of at least my own objectives.

Here you go.

quote:
--------------------------------------------------------------------------------
The idea of a biofilm protecting the anaerobes is an intriguing one--but if these are strict anaerobes, to which oxygen is toxic, the biofilm will gradually erode as the uppermost layers are exposed to oxygen and die and decay away. Of course if we are dealing with "facultative anaerobes" this is not the case because these bacteria can live with or without oxygen. Being as no one has a great idea of what bacteria are at work here I would hesitate myself to make a statement about the effects of drawing oxygen through the "anoxic layer".
--------------------------------------------------------------------------------

I absolutely ABHORE the idea of drawing oxygenated water through the "Anoxic-zone" ( no oxygen ). In fact, if oxygenated water is drawn through the "no-oxygen" zone, then it isn't "Anoxic" anymore, is it? Sounds like a bad idea.

quote:
--------------------------------------------------------------------------------
And if you have some sand stirrers they will perform this job sufficiently.
--------------------------------------------------------------------------------

Good idea, I agree.

quote:
--------------------------------------------------------------------------------
Another thing to consider--in all of these proposed systems there is live rock being incorporated, am I correct? In that case, you really can't measure the actual effects of drawing water through the sand bed because in essence the LR is performing the same function. If the sytem works, is it because of or in spite of the plenum wasting? The only way to know for sure is to include no rock in the system at all.
--------------------------------------------------------------------------------

I don't think that is true. In my particular case, the plenum was installed about 5 mos. ago, but I have not drawn any water from it yet. My Nitrate has varied from as high as 80ppm down to 1ppm, but is now at about 5ppm. Phosphate has been as low as .5ppm, but is now at 1.5ppm. I have kept a rather steady ( and high ) bio-load for several months now.

If the "wasting" is able to improve Nitrate processing over a "standard plenum", then that effect will be observed over a period of time, by checking Nitrate in the "water column", after wasting begins, and continues.

Phosphate export is "almost guaranteed" to occur ( or be monitored )by way of it's presence in "the effluent".

Unlike ammonia which can ultimately be converted to gas which bubbles off, phospates can only be incorporated into the bacteria. Ultimately the DSB acts as a sink for phosphates, sulfur containing compounds and heavy metals. This is thought what acts to ultimately cause DSB's to crash. The sink gets full and starts to leak nutrients back into the water column.

Exactamundo!!!!!! . . . . unless the"sink" has a "drain"! :thumbsup:

Ok, now a dumb question--if we know phosphates can be processed in a fuge with macro, and we know DSB works well on its own processing nitrogenous wastes, at least for a time, why bother with plenum wasting?

While I agree, that Phosphate will be "bound" in a refugium, for subsequent removal by harvesting and/or pruning, that does not stop phosphate from being processed in the substrate also.

The primary reason for plenum wasting, is to "avoid the crash". The secondary reason for plenum wasting is to achieve improved Nitrate processing.

>>
>>>>The reason for having substrate, is "FOR THE CRITTERS THAT REQUIRE IT!!! . . . . NOT for "processing ". :hammer:
>>

I hope this is helpful, > barryhc

:beachbum:

 

["Umm fish?"]

Another thing to consider--in all of these proposed systems there is live rock being incorporated, am I correct? In that case, you really can't measure the actual effects of drawing water through the sand bed because in essence the LR is performing the same function. If the sytem works, is it because of or in spite of the plenum wasting? The only way to know for sure is to include no rock in the system at all.

I think that it's pretty unlikely that the stuff that gets deep into a deep sand bed will ever get out again. I can imagine some of it being pushed back out with the nitrogen bubbles, but not much. And I don't imagine that the bacteria do a lot of traveling between strata. So, unless there are some sand stirrers that are really pushing stuff around, I would think the live rock has a pretty minimal effect on processing anything that's managed to make its way all the way down to the manifold.

So, by testing the water you wind up pulling out from down there, you ought to have a pretty good idea of what frequent wasting is doing for you.

And as for me, the less frequent waster, I always expect the water will be disgusting....

 

[Obi-dad]

I still think having a drain with a DSB is way more complicated than having a drain with an SSB - and having the DSB external to the display (such as in fuge or even Calfo-style bucket), or even not having a DSB at all if you have sufficient live rock to do all the denitrification.

I am not bashing anyones' attempts to get a drain to work with DSB, just remarking that it gets very complicated trying to maintain the anaerobic layer, and worrying about how much, how often, whether you are hurting the anaerobes, etc. IMO, much easier to keep the DSB external (or not use one), and use the drain on the SSB to keep it from filling with gunk.

If you keep the DSB external, you don't have to worry about your display crashing, and can change the DSB out easily.

 

["Umm fish?"]

Ok, now a dumb question--if we know phosphates can be processed in a fuge with macro, and we know DSB works well on its own processing nitrogenous wastes, at least for a time, why bother with plenum wasting?

A refugium can only bind the phos that gets to it. That is, the phos has to be in the water column. I will of course be running a 'fuge and will be trying other strategies to attempt to make sure that detrius stays in the water column as long as possible. But what we're trying to accomplish here is to figure out a way to get rid of the phos that gets stuck in the sand bed.