Plenums and the wasting "option"

[wave98]

Hello all:

I'm pretty new here and had gotten a "wasting type" of plenum installed before I graced the pages here at RF. I had come across the idea on another site, and then found some discussion here, that ran on for over a year, and then just sort of died without coming to any real conclusion.

That thread eventually became constrained to detritus removal primarily, with a lot of supposedly "given", "can't do this because", and "can't do that either because", statements and viewpoints that left the thread sterile and the concept basicly untried.

I am not so concerned about "detritus removal", as it was dealt with previously because I believe that it should be handled with flow and suspension in the water column, which is already important for other reasons.

Further, I am not promoting plenum's, or their "wasting", as a cureall to anything, and various other systems will need to be utilized to complete the system. All other systems are welcome to be included, ie. vodka, reverse flow, phosban, skimming for sure, refugium, UV, and on, et al.

It simply appears that not enough investigation and "discussion" has been applied to this potential option in general, other than some people "chucking spears at it". There are some people investigating it to the degree that they can, under the "cross fire".

My interest begins with actually wanting a substrate to begin with, for it's visual appeal, and the creatures that live in it ( gobies-shrimp, jawfish, cukes, starfish, etc.).

From there, how can we best maintain, or even "control" the functioning of a substrate, to whatever degree we can, and remove some nutrients and "chemical sink" compounds while we're at it?

Now I'm not much for getting into "debates", in fact I particularly abhor them, and highly prefer intelligent discussions.

MikeS is looking at his "occasional flush" method. ( suggested by Mojo )

I am in the "High Frequency Plenum Wasting" camp, which I just created( if no one else wants take credit for it )!

Aqurium debacle has his vodka "enhanced" reversed flow version.

Mojo and others just gave up and went BB.

I see particle size and bed depth as important starting points, which are related to and affected by flow, wasting rate, and frequency.

The substrate certianly does not need to be homogeneous IMO, and layering could go a long way toward solving various problems that the unconvinced are concerned about, and which the "naysayers" chuck spears at! :idea:


Well, that ought to get us started, and if it gets too messy here at the beginning, I will get some current posts from other threads that are ongoing, pulled into this so people can bone-up on some of the issues that need to be addressed.

Thanls to all, and happy reefkeeping! - - - Wave98

 

[mojoreef]

Wave I figure we should just keep the thread moving here instead of both threads going at one time.
As far as I am concerned if a person likes the look of sand in thier tank then thats good enough for me, so no argueing from here.
Using good flow to keep detritus in suspension for removal via a skimmer is a good plan and will really help with the bioload of the bed system. The reason I started the original thread on making a sand bed system work is because so many people enjoy them and it would be nice to see a system like this be long term sucessful. Better then just turning a blind eye.

Anyhooo for me their are a few concerns I have with any sand system.
1: is keeping the top layers areobic
2: removing end product detritus
3: is dealling with P effectively

When water is suck down through the bed you have a shot at taking care of problem 1 and 3. New oxygenated water with help the aerobic zone and pulling water down will also slow down the P leaching. Having a system under the bed to remove solids will also help problem 3.
So things I learned when playing was getting the water to diffuse through the bed evenly, was a bear and I had no luck with the finer sand. the other was to find a viable system to remove the end product detritus which will eventually clog the system. I notied you mentioning frequency alot, can you tell me a little more about this?? and then if you have any thoughts on the problems I encountered.

thanks bud


MIke

 

[MikeS]

I am not so concerned about "detritus removal", as it was dealt with previously because I believe that it should be handled with flow and suspension in the water column, which is already important for other reasons.

Ahhh yes, detritus is the key ultimately...the more waste you can remove manually, the less work you'll put a biologically based reduction system, like a substrate, through. And the better off you will be for it. We can have perfect flow, low bioload, good mechanical removal, and you will still accumulate these things in the substrate, it's unaviodable. Maximizing these mechanical aspects of detrius removal will simply aid in long term maintenance of the substrate, it will not solve the problem alltogether. And since detritus accumulation is the root of all evil in our substrates, via byproducts, diffusion inhibition, ammonification, ect....it is a VERY important issue to be concerned with...

Further, I am not promoting plenum's, or their "wasting", as a cureall to anything, and various other systems will need to be utilized to complete the system. All other systems are welcome to be included, ie. vodka, reverse flow, phosban, skimming for sure, refugium, UV, and on, et al.

And that's an important point. There really is no "cure all" system for reeftanks (although DSB's were promoted as such 5 years ago when I added mine ) Any biological or mechanical system of waste management needs to compliment the system as a whole, and its limitations need to be recognized as well.

It simply appears that not enough investigation and "discussion" has been applied to this potential option in general, other than some people "chucking spears at it". There are some people investigating it to the degree that they can, under the "cross fire"

Well, it's a reletively new thing to the hobby. And one of the best ways to investigate the logic behind something new is to "poke holes" in it so to speak based on factual evalutaion. Personally, I'd like to see the downsides before I persue it, I've got myself in LOTS of trouble in the past 20 years of marine tank keeping by diving into things without fully understanding them first....

My interest begins with actually wanting a substrate to begin with, for it's visual appeal, and the creatures that live in it ( gobies-shrimp, jawfish, cukes, starfish, etc.

As do many of us....I too like the looks of a substrate, and I feel my clam, LPS will benefit form a substrate...

From there, how can we best maintain, or even "control" the functioning of a substrate, to whatever degree we can, and remove some nutrients and "chemical sink" compounds while we're at it.

This is the meat of what we will discuss in this thread for sure. Substrates can be maintained, but control is a whole new ballgame. There are so many different things taking place biologically, all interacting and affecting one another. There are a multitude of mechanical things in the tank that affect the great number of biological processes on top of that. It's such a vastly complicated thing, it can't be controlled. But, it can be maintained in a fashion that promotes a long term situation. Ultimately, however, it has a lifespan....what we want to do here is try to increase the lifespan of a chosen biological sytem...

Now I'm not much for getting into "debates", in fact I particularly abhor them, and highly prefer intelligent discussions.

As do we...a debate is a civil exchange of ideas and opinions, when those fail, it turns in to an arguement...

MikeS is looking at his "occasional flush" method. ( suggested by Mojo

Yes...I'm doing it so I can "refresh" the system from time to time, remove some detritus and byproducts, ect. in an attempt to lenghten the effective lifespan of the system. I still think we need to get deeper into the effects of low oxygen (not deviod mind you) on nitrate reduction.

I am in the "High Frequency Plenum Wasting" camp, which I just created( if no one else wants take credit for it

The very first thread I read on the subject was a fellow who did frequent drawoffs on a wasting plenum, the idea has been around awhile...I'll find the link...As stated above, I think we need to clarify "anoxic" (ie low oxygen) and how this aids/hinders denitrification, and we need to talk a bit about the mechanical issues of frequently drawing off the plenum and possible detritus compounding...

Aqurium debacle has his vodka "enhanced" reversed flow version.

well..... :doubt:I'm not going to go there...

Mojo and others just gave up and went BB

Well, mojo gave up on it long before many of us even ventured into it...and for good reason, because of their compexity, they can be difficult to maintain and virtually impossible to control...if I was doing a large SPS tank, I'd likely consider the BB method...

I see particle size and bed depth as important starting points, which are related to and affected by flow, wasting rate, and frequency.
The substrate certianly does not need to be homogeneous IMO, and layering could go a long way toward solving various problems that the unconvinced are concerned about, and which the "naysayers" chuck spears at!

Layering is going to ulimately inhibit diffusion in and out of the bed. You'll have migration and porewater issues, ect... A single, uniform gradation substrate is IMO much more ideal for promoting the things you want to happen in there...

Well, that ought to get us started, and if it gets too messy here at the beginning, I will get some current posts from other threads that are ongoing, pulled into this so people can bone-up on some of the issues that need to be addressed.

Thanls to all, and happy reefkeeping! Wave98

Good post wave....lots of details to wade through here...In the big picture, however, I think it is important that any substrate type, be it DSB, plenum, SSB, ect...fills the role of merely "complimenting" the overall system, and not be the dependant factor. And this is coming from the proud owner of a 5 year old DSB... :lol:

MikeS

 

[wave98]

All points well taken Mojo, and Thanks. ( read on )

Points well taken again "O Dark Lord". ( your avatar just "cracks" me up, by the way ) :lol:

OK, here it goes!

I'll tell you about my current system here, and future systems that are "waiting" for some "direction", so we can get some of that out of the way. At this point I am running a 27 gal. hex ( about 18 gal. of actual water )that overflows to a 16 gal. walmart tub, and has 400 gph returning to the hex with diffuse flow. This tank has a carefully designed and nicely installed "wasting" type of plenum, with various layers of aragonite substrate, totaling about 6" depth. ( darned "sea-clown" that has to be replaced very soon )

The plumbing is 1/2" PVC and is capped off at 9" above the substrate, so for now, it's just a plenum. I am a life time engineering student of the "School of Hard Knocks" ( no damned piece of paper yet though! ) About 30 years of this, so I can help a lot with the mechanics of the plumbing. We'll get into that whenever you are ready.

I have 8 mos. on this system now with very little trouble, and I have a little of just about every kind of critter you normally see in reef tanks included. A few SPS frags with only about a month on them, and they are telling me that 96w pc's aren't good enough ( even at only 4 to 8 inches under the bulbs ), and that 15 ppm N isn't their favorite version of "smog" either. I have a lot of work to do here, and I'm going as fast as I can.

I am pretty stingy about feeding( more so than I would like ), but all the animals are happy.

I ended up with over 25 crabs and 25 snails in here due to a shipping error, and I have never had an algae problem, including curing LR right in the tank with the other animals about 3 months ago.( Boy, that ought to start a fire! )

Anyway this is my little experiment, and it is doing just fine thus far. I realize that I have about a year to go before I can call it truly "established". As soon as I can finish the wasting plumbing outside the tank, I,ll begin some "wasting". This might be a couple of weeks since I have to finish up "summer" real quick.

All I can do at that point is to check the effluent for levels, and learn more from you guys and wherever. We might not know that much from this for quite a while, since substrate problems usually take quite a while to develop. We might get lucky, and see some P and N reductions early on, and that is what I am looking for, but long term stability by definition is going to take a long time.

OK, so for the future systems, I am looking at 90 to 120 gal. for specimens that are not "reef friendly", like triggers, moray, lionfish etc. Then there is the 200 to 240 gal. system that accomodates the widest variety that I can muster. They have their spaces waiting in the "Diver's Den", but I have a lot of learning to do before I "commit", primarily to the substrate system.

I am quite a "planner", and that is what I am doing here. The plan isn't finished.

All right then, so as I see it, every consideration here has to fit in with the rest of the system. This is not an easy task, and boy don't I know it. For my version, I am obviously complicating it quite a lot with the requirement of the sand dwellers, but that is where I am starting from, and I am not backing away from it!

This is getting a lot longer than I would like, so I'll try to summarize and see where we go from here.

Now, in my particular case, we start with the sand dwellers, as I have indicated, and they have to have some substrate to live ( and thrive ) in. Well we just opened a whole can of "worms" here, now didn't we! And that just may be an important part of the solution. Micro stars, cukes maybe, all the little "critters" that are hard to see, for sure. I know it's hard to match mother nature here, but "they" are helping us here aren't they, even if not as much as we would "like"? I am here to learn.

So, now we have this substrate "mess" at the surface. Well, a little bit of "rubble" will help in the areas that the gobies and jawfish don't destroy! A screen, at some depth, will leave us with some substrate underneath that we hope is representing our "low oxygen zone". ( Anoxic is fine with me, if Mojo will allow it. )

Now comes the good part, in my estimation ( or the crux of the matter if you prefer ). So were not helping the "balanced flow" that we're looking for here with this "mess" that we're making in the "upper level". S-o-o-o, I'm not sure how this affects MikeS, with his occasional flushing( although I think it might be similar ), but for the HFPW( okay, High Frequency Plenum Wasting ), we want the area below the protective screen to remain "low oxygen" to support our faculative (denitrifying) bacteria.

Below that (hopefully) we have the anearobic ( or devoid of oxygen ) zone, where we can attempt to manipulate it, to some degree with "wasting" and or even filtering, to be done at whatever flow rate, volume and frequency that gives usthe best results.

At least we have some options with a plenum that is plumbed into the system, since we can use it for wasting or filtering or flushing( forward and or backward ) or feeding or whatever else new bell or whistle that we come across or 'invent". God thats a lot of "or's" in one sentence, but we have some options here that we don't have in a standard plenum, or deep sand bed, and I guess that is my main point. We haven't found an optimum system yet ( and "utopia" does not exist either ), but at least we have something that we can "work with", to what ever degree.

My reason for high flow, is that, it allows you to keep the flow balanced across the entire plenum area. The high frequency is intended to simulate continuous flow, because true continuous flow causes a nightmare in the flow balancing. This causes flow lengths of time, to be in the range of only a few seconds, since the downward flow rate has to be rather low to maintain the bacteria populations at the preferred oxygenation levels and depths. :idea:

OK, so Mojo, I am not really very knowledgable at all about diffusion, and I'm sure you can help me a lot here. It also, is exceedingly important to long term stability, and needs to be incorporated into the design.

I expect to put in one of the two larger systems in the "deep of winter", and we won't really know anything about long term stability for a very long time after that. The best I can do, is to learn as much as possible in the next few months, and then go ahead and "take a shot at it"!

O Dark Lord, and Mojo both, where do we go from here? Wave98

 

[aquariumdebacle]

I want to stress that the "alcohol wasting" refers to the owner and not the clients. I would like to install the feeding apparatus but may not use it or use it sparingly. I am not going to approach the phosphate issue until I can get some substantial plant life. Got any Caulerpa Mikey? or should I get some from Anthony?

God created alcohol to keep us Irish from ruling the world!

 

[wave98]

Too bad he didn't put more effort into it! Good luck > Wave98

 

[mojoreef]

Danny we couldnt rule the world brother.... We have no place to put all the prisoners!!!!!!.

Wave as I mentioned prior, I had problems with getting proper diffusion evenly through a fine particle bed. Now in saying that I wasnt dealing with a wasting system, I was looking more to remove end product.
I got kind of an abstract idea, maybe a little off topic maybe not. What if we installed, say at the 1 inch deep level in the dsb a very thin tubing system perferated with a ton of small holes. The flow going through these holes would be fairly low, just enough to keep the upper one inch aerobic and to allow for the lighter detrital products to be forced up instead of sinking to the bottom. With the proper spread on these tubes we could allow for gaps...say every couple of inches?? this would allow for the transfer of soluable nutrients to migrate down for denitrification??
A couple of things this could help us with.
Keeping the aerobic zone aerobic would now not be an issue.
Any extra food or particulate detritus would be forced to the surface and thus kept in suspension.
The gaps would allow for soluable nutrients to migrate down wards
Would assit in the process fo migrating gasses out
Would keep the upper level at a higher ph which would keep the binded P in check.
Still allow for critter to migrate at thier leasure??

Anyway just a side thought, what do you folks think??


MIke

 

[NaH2O]

I'm not sure, Mike. Seems like a modified version of the reverse flow UGF?? The way I'm looking at it......it would make more sense to create a good plumbing/flow/circulation plan in order to keep detritus and wastes in suspension, and keep up a good maintenance routine for stirring up the aerobic layers of sand. I would also be concerned about maintenance on the tubing. If part of the system breaks-down, then it is a mess to pull it out to service (if it gets clogged, for example).

 

[wave98]

Well Mojo, if "oolitic" is close to the "fine particles" you were having diffusion problems with, then I'm not surprised. High Frequency Plenum Wasting ( HFPW )will certainly cause a relatively even "flow" across the whole tank "footprint", and definitely keep your upper zone aerobic. This "simulated low flow" is not diffusion, but it should help to even things out a good bit. It can pull through anything including powder mud, which I'm not suggesting, but very fine particles from top to bottom will promote channeling, which is why I favor some layering.

I need some links and articles on diffusion. How does diffusion go up and down at the same time anyway?

As far as your brainstorm goes, I can see how the functions would work there, although, I'm still trying to get some nasty out of the bottom, and this isn't helping us there very much. It would work as you say for the most part, and it would be interesting to add to another version of the system.

I have to agree a bit with NaH20 partly here. in that over a period of years, with any substrate melting going on, it is going to sink more and more. Im not sure if that is valid or not. ( controversy ) As far as clogging goes, maybe that too.

The HFPW should not suffer from this since the is plumbing is protected, and 3 times a day doesn't allow enough build up to clog the tubing. I think we might want to use some occasional flushing, like MikeS as well, but maybe once a month, and reverse flush right after, each time to make sure of no clogging.

It's a good out of the box thought, but really Mojo, I really have to bone up on diffusion, as well as bacterial detritus ( end product ) bio-film, mulm, etc. before I can really respond properly to a lot of this and then further the design. I hope you read my post above ( #4 ) carefully, because it covers just about everything I've got to offer here, until I do the boning-up on diffusion etc.

It's the plumbing part that I'm particularly comfortable with, but there is a lot of controversy about the depths at which these bacterialogical processes are taking place. I've never even seen a deep sand bed except for pictures, nor a DSB or plenum when it is being torn apart, so, at what depths do these processes occur in different grain sizes, and at what depth do these horrid goop, glop and petrifications occur.

Once I find out a bit on these issues, my potential responses will become more meaningful, and the design, much closer to completion. I've only got about 4 months before I take the leap! Wave98

 

[aquariumdebacle]

Mikey, I like your idea of replenishing the aerobic zone, hadn't thought of that. Maybe in conjuction with a deeper anaerobic feed to the bottom substrate. None of this will address the phosphate leaching problem which is endemic in a anaerobic part of a system. This might be solved by having a seperate anaerobic filter with an inert material as substrate such as a very long length of smal tubing.

 

[mojoreef]

I'm not sure, Mike. Seems like a modified version of the reverse flow UGF??

not really, the tubing would be only down and inch and blowing outwardly.

Maybe in conjuction with a deeper anaerobic feed to the bottom substrate. None of this will address the phosphate leaching problem which is endemic in a anaerobic part of a system

Well I dont know about that. Phosphate leaching would be due to the melting of the sand itself, having a zone where the ph was kept high will cuase it to percipatate back o to a seed surface?? I thought in conjunction with the plenum wasting system it might be something to look at.

Anyway Lets get back to Waves project here we can play with this idea another time.

Wave I am not sure what you mean by high frequency?? and what particle size are you looking at. Let me know and I will look into some diffusion models.


Mike

 

[MikeS]

A lot of varibles are going to come into play when discussing diffusion...it's a very dynamic situation, it will be extremely diffficult to come up with a mathematical model that will be applicable to most tanks...

Wave98, I'm assuming by "high frequency" you are referring to a system where you are drawing off the plenum on a fairly regular basis, ie daily or weekly, correct? And I also assume that the primary reason you wish to do this is to continue to introduce oxygenated water into the plenum, correct? I'm just trying to get at the meat and bones of what you are trying to accomplish with your system...

Mike....I think the airline idea definately has some potential....we can work on that one in a seperate thread perhaps?

MikeS

 

[NaH2O]

not really, the tubing would be only down and inch and blowing outwardly.
Mike

Well, I said modified, didn't I ? Besides, you didnt indicate which direction the flow would be blowing. I guess I don't get it. The concept of the reverse flow UGF is pretty much the same, I thought. Blow the flow upwards to keep detritus from settling in the bed.....this seemed like a modified version of that. I'll wait for the new thread....

Back to the regularly scheduled topic

 

[wave98]

"High Frequency", is a necessary substitution for "continuous flow". Let's say for now, that the maximum wasting volume is 33% of the water volume per month. For my 34 gal. of total water volume, that is 3 pints per day. If the frequency was once per day ( and my tank has 270 sq. in. of substrate surface ), that would equate to 5/16" of downward flow through the substrate each day.

So, that could be 5/8" every other day, or 1/16" five times a day. High gph flowrates are necessary to keep the flow evenly distributed( and avoid "channeling" ). This requires rather short flow durations. At a frequency of three times per day ( one pint for each "draw" ), and using 90 gph for a flow rate, we get a five second flow duration for my particular setup. So that would be a downward flow across the entire substrate area for a depth of 7/64" ( just under 1/8" ), for five seconds, three times a day.

How are the bacteria going to react to this? At what rate does "upward diffusion" occur? H-m-m-m . . . Frequency remains as a very important variable in this design. I assume at this point, that "products" that will be reintroduced into the water column are going to come from the upper high oxygen zone and to some degree, from the low oxygen zone under that. Products other than nitrogen gas, would hopefully be "wasted" from most of the "devoid of oxygen" zone.

We don't know yet, what depth these zones will extend to, but some early oxygen level testing ( along with flow duration experimantaion )might give us a clue at least to how deep the low oxygen zone extends. This may also give us a clue as to how much of current bed depths are really contributing to denitrification, and how much represents a larger "chemical sink", that just takes longer to fill up.

So much for "frequency" and oxygen levels in the "plenum"( none ).

MikeS . . . The primary reason for forced "simulated continuous" downflow, is to improve denitrification through increased surface area ( greater depths ), and eliminate some "chemical sink" compounds via "wasting".

Mojo . . . "Critter comfort" in the top several inches is probably going to make a mess out of trying to pick diffusion models, but anything you can find would be a big help. OK, lets say 1-3mm, 1-4 mm, 2-4mm, 3-5mm( Mikes favorite ) or whatever you can find. Some "experts" say we are not getting more than 1/4" deep in oolitic sand unless critters move the zones deeper, I sure don't know, but I expect to find out eventually.

Aquariumdebacle's post about his 2 year tear down in the "vodka dosing" thread is kind of interesting in that respect, although his associated "breaking in" procedure seems like a nightmare. Maybe I'm just gullible, and there's nothing but humor to be found in that post. Anyone thought about dosing beer? :lol:

And so? . . . Wave98

 

[wave98]

OK, so another "just too damn long" post from "the Wave". Sorry about that. Here, let's try this:

"High frequency" is going to start out at 3 times per day with one pint per draw, for a total of 11 gal. per month, which is 1/3 of my particular water volume.

Particle size is going to be for "critter comfort" in the top 3" anyway( probably a mix of oolitic to 4mm ), and that is because, of course, that "critters" are my first main reason for having substrate. Below that( including a screen for critter control ), maybe we can do some good regarding the substrate grading. Let's say 3" more inches of 2-4mm or 3-5mm.

I don't believe at this point in my education here, that I am looking for any oxygen in the plenum, as that would represent a "nitrate factory", if diffusion can travel upward faster than the average daily downward flow rate.

Is that a little better?

Thanks for you input, and happy reefkeeping! Wave98

 

[DonW]

I'm not understanding this entirely but it sounds alot like my first tank. It came with a coil of 3/8 tube laying flat across the bottom like a coiled snake. The tube was perferated with 1/8 holes all facing toward the center of the coil. One end was plugged off and the other went to a petcock in the bottom of the tank. There was a tap that connected to a air pump. All this was under the sand, screen and eggcrate. Supposedly you were to open the petcock twice a week and drain one gallon and top off with fresh saltwater then you would run the airpump 10 minutes each day.
The set-up was supposed to have been invented by the shop owner and he would upsell it with the SW tanks.


Is this the type of set-up you guys are talking about?

Don

 

[wave98]

DonW:
A 3/8" diameter tube with 1/8" dia. holes in it, is only going to feed water "evenly" for something less than 9 holes worth of tube length( probably only about 6 holes ). I don't know what size of tank you are referring to here, but for anything over about one gallon, I think you would run into quite a flow distribution problem.

Actually, I believe that flow distrubution is the foundation upon which any permutation of "plenum wasting" must lie, and I have really been trying to get to that issue, and get people to understand it, so that we can move on to the subject of advection flow, forced downflow, and diffusion rates.

Understanding these aspects of "processing" in any substrate, will lead to some sort of "control"( sorry MikeS ) or management of the substrate that will be beneficial to the life expectancy of the "system".

Of the members who post on this forum, Anthony Calfo seems to have the most balanced and realistic view on what is occuring in a substrate, particularly what is or is not likely happening as a result of the populations of "sand stirrers", and the microfauna or "whatever fauna" that populate the substrate, and what we might expect of them, depending upon how we choose to supply them. That, and of course who and how many that we allow to "predate" on them.

So, I assume that the tank you are referring to was not a one gallon, and that the "tube thingy" didn't work out too well for you. No surprise. :lol:

Now, as far as the air pump "silliness", you can read posts #14 and #15 in this thread regarding oxygen in the plenum.

Any more questions Don, just ask away! :exclaim:

Wave98

 

[DonW]

Wave98,

The coiled tube was nothing more than a drain that pulled water from below the plenum. It did drain out some nasty slime also it pulled sand down from the surface. You could watch the small divots occure while draining. The air pump would cause water to be pushed back up.
I assume the theory was that it would stir the substrate. While the air was running any detritus stirred up where the skimmer was supposed to take it out.
This was a 43g hex and was its only source of biological filtration (FO no LR), the tank did fine so I'd say it did its job. Although I dont claim to fully understand sandbeds, I'm just following along.

Don

 

[wave98]

DonW:
For fish only, you could run RUGF, or Bio-balls, no big deal. With or without live rock, although I would recommend the live rock.

What I am looking for from this system, and this thread, is to improve NNR, reduce "deep bed nasties", and improve "substrate system" longevity.

Anyone who believes that "substrate systems" are nothing but trouble, need to run bare bottom systems, and many do so with very good results.

Finer grains at or near the surface keep detritus that is generated in the water column at a minimum. Anyone who is unhappy with "sand storms", needs to diversify their flow, and can further eliminate such "storm" problems with some "rubble", or 1-4mm "stuff" at the surface. Those who want to further cry "bloody murder" about detritus accumulation at the surface, can add a bunch of snails and crabs to keep the substrate surface, and also that of their live rock nice and clean. I would reccomend them anyway.

I am still in the "layering camp", as far as substrates go, and that does not mean that I consider "layering" to be the easier way to go in general. It just seems to me that if we are going to be utilizing the "wasting option"( and that is what I am promoting ), with high gph rates and "high frequency" wasting schedules, that we can do some things that were not available in a "static pore water flow" system. I am insisting on a substrate selection that is conducive to sand stirring creatures( gobies and jawfish etc. ), so i just don't have the BB option.

In other words, dynamic and controlled flow, downward in a substrate, offers options that are simply not available in a "throw it in" and hope for the best system, which is what we are left with in a static ( no ) flow system, which is the only other option, if you intend to run a substrate, which I do.

It looks like I had best just start the "wasting", and check the oxygen levels, along with P and N to see what is happening at the initial target wasting rate of 33% monthly, and 7/64" per "draw" of downflow 3 times a day.

Thanks for you inputs "all", - - - Wave98

 

[DonW]

I guess I'm not getting it. How about some pic's or diagrams. Can we see the nuts and bolts of "high frequency wasting"? What formulas were used to come up with the measurements and why?

Don