Hmmm anyone want to talk about this one??

[mojoreef]

Whats that suppose to mean?

LOL it was just a joke Jid. When I get some time I will copy it over for ya.

chris&barb
I hear ya, all those system will work and have thier limitations. I would imagine that you are aware of those limitations and have a good idea what to look for and what to watch for. This is my point to the whole thing, when dsb's first came out they were touted as virtually maintence free and would last for ever (some folks still preach that) now through the process of the internet, you get an expert that gives up pretty loosly put together info, incomplete at best, then you get folks that follow their every word and relate that info to others (watered down, or at least their opinion of the system) and you end up with a whole bunch of new folks that go in totally blind and ultimatly fail because of it. Now if they were given the true story (both the good and the bad) they would have a much better chance at sucess.
This kind of thing is the reason we started up RF, to try to tell folks the inner workings of all sorts of things, hopefully it still remains that way.

Mike

That's exactly what angers me about that "study". These guys went into it with a bias, and then make inferences based on their results

Mike what they are doing is the way it is done in thier world (scientific). You dont start with a problem and then try to figure it out. You DO start with an answer (they call it a hypothisis) and then fill in the info to prove your point. Then you through it out for peer review. This would then result in a series of new reports to disprove it, then the replies to them and so on. When this kind of mentality comes into the lay world its one report and thats it, then woth some of them when you come out and prove the reports incorrect you get attacked by the minions and told by the expert to "Not let the door hit you in the A** on the way out" lol.
I just wish more folks would be willing to talk about this kind of stuff more often. Maybe we should start up another forum to review these articles?? hehehe

One last note. Rob Toonan is a very smart guy and one of the better ones out thier, thats kind of way it was a little bit more of a shock this time.


Mike

 

[sanjay]

One last note. Rob Toonan is a very smart guy and one of the better ones out thier, thats kind of way it was a little bit more of a shock this time.

Mike

Mike:

Why don't you invite him to answer the questions, before trashing him and this "research".

You are absolutely right about the other comments you made.

sanjay.

 

[mojoreef]

Hiya Sanjay. I dont really have any questions in regards to the research/study/article, It is what it is and is spelled out with in the work. I talked with Rob about the whole line of stuff he was doing and going to do in regards to plenum vs dsb which was what started all these articles. My rant was more of an in general thing on some of the material being produced and put out to the general masses. In Robs case it is as I mentioned above in the way the scientific community approaches things, problme is that thier will be no review or counter arguement so to a lay person in most cases it something that is carved in stone.
Some examples, an article gets written stating that Reef tanks should be run at temps of 86, a bunch of folks read it and begin to follow the methodogy and thus hundreds of tanks crash.
Another skewed study on salt mixes poisening our tanks, folks read it and change to the salt promoted, results? hundreds of tanks crashing.
Studies and articles on how to run a dsb, No limitations, no guildlines?. Hundreds of folks going in blind and screwing up thier tanks and being plagued with algae and other nasties. Aurthor simply reversed himself, no problem, but the pain folks went through was pretty tuff.
Skewed studies on coral feeding? results? folks nutrient loading thier tanks and running into nothing but problems.

Anyway the list goes on and on. I think folks who hold those or who have taken up those positions should try to operate with in the world of the layman?? Just spill the facts on both sides of the equations instead of using a scientific approach that doesnt work. Kind like a feelow I know that produces solid info on lighting???


Mike

 

[MikeS]

Mike what they are doing is the way it is done in thier world (scientific). You dont start with a problem and then try to figure it out. You DO start with an answer (they call it a hypothisis) and then fill in the info to prove your point.

Ok, this study was a follow up to a previous one, and here is what I would consider as the point to the study...this quote taken from the first study...

However, there has never been a comparative experiment to determine the relative effects of sandbed depth, particle size and whether or not the presence of a void space beneath the sediments confers any advantage relative to the presence of the sediments themselves

I could not find a statement anywere in the presentation where they initially claim that the plenum offers no advantage over substrate alone as an actual hypothesis for the experiment, although that does seem to be a theme later when discussing the results and thier conclusions...

Put simply, our experiment shows that the presence of a plenum has no measurable benefits over simply depositing the same sediments directly on the bottom of the aquarium (at least for nano-tanks over the time scales that we tested).

Ok...on the statistics...as I read it, they first compared their test results to the AutoAnalyzer results to determine mathmatical correlation. These test results (or dependant variables.... ie the salinity, pH, ammonia, nitrite, nitrate, oxygen, phosphate, alkalinity, and calcium) were then compared to the independant variable in each tank (ie deep, shallow, fine, coarse, plenum, no plenum) and were analyized with statistical models to determine whether the differences between the observed dependant variables were statistically significant enough to infer correlation with the independant variables.

Here's what they found...

Analyses of variance for each water parameter revealed no significant differences among the final salinity, ammonia, nitrite, oxygen, or organic concentrations, nor were there any significant interactions among experimental treatments for any of these water parameters

So the independant variable did not correlate with the dependant varible in these cases.

There were significant differences among treatments for the remaining water parameters

In the cases of pH, nitrate, phosphate, alkalinity, and calcium, there was a statistically significant difference between the dependant and independant varibles to correlate between them.

I find it worthy to note that livestock mortality was not listed as a dependant variable in the initial statistic summary, but it is inferred to later in the study, they did do some analysis of it...

For the among treatment comparison, the overall analysis of variance was not significant (df = 7, F = 0.88, p > 0.5). However, there were nearly twice as many animal deaths overall in shallow as in deep sediment tanks (Fig. 9). On average 2.91 ± 0.46 animals had to be replaced in the shallow sediment treatments, whereas only 1.47 ± 0.46 animals had to be replaced in the deep sediment trials (df = 1, F = 5.23, p < 0.05). No other treatment or interaction term significantly affected the death rate in our experiment.

Basically, the mortality rate between tanks could not be correlated to the independant variable in a statistically significant manner.


On the whole, based on what can be inferred from the results of their experiment, these statements in the Overall Summary are the ones I have a problem with...(and lets face it, many people are going to breeze through the bulk of the article and focus on the overall summary, particularly newcommers to the hobby... )

Overall death rates were roughly twice as high in aquaria with shallow sediments as in deep sediment treatments. The highest overall death rates were seen in aquaria with shallow coarse sediments over a plenum, and the lowest death rates occurred in aquaria with a sandbed composed of deep coarse sediments.

While this is their actual observation, it was NOT supported statistically that the reason the mortality rates in these tanks were due to substrate type. I think they should have made that point VERY clear in the summary! To read that summary, one might infer that the substrates correlated directly with mortality, which they simply didn't to a statistically significant degree.

We did not test bare bottom tanks, but the data clearly suggest that the shallower the sediment, the higher the mortality rate

Whoa! Sure, they observed higher mortality in shallow systems, but as stated there was no statistical significance there, so one cannot infer with any degree of certainty that substrate depth and mortality correlate...which leads to this...

and you can't get much shallower than a bare bottom tank!

Whoa! Now this is a big stretch! First, it wasn't in the test, so why even make a reference to it? Second, since no significat relationship was demonstrated on mortality, how can one possibly infer that?

MikeS

 

[MikeS]

I wanted to add this to my last post...

I was perhaps overcritical of the study to begin with, and my terms "laughable" and "joke" are probably too harsh...I tend to get a bit carried away from time to time, it's a personality flaw of mine... :lol: But hey, I'm big enough to admit it

Also, I got a bit off on a tangent in my orgional post concerning particle size, the more I look at it the less I think their choice of particle size on the coarse end compared to what I was saying would have had an impact on the results...again, my tendency to get carried away with myself... :lol:

I do still however, think this study has some considerable control flaws, a misleading summary, and not a great deal of application to these condidtions in the hobby in general.

Our experiment shows no evidence for any of the espoused benefits of a plenum (reviewed by Goemans 1999) either with or without live animals in the design. Instead our results suggest that any benefits seen are a direct consequence of the presence of the sediments themselves rather than the void space beneath it.

Ok...when we talking about a 3 gallon nanoreef set up similarly, with a similar bioload, maintained in a similar manner and observed over a similar period of time....sure, I'll buy that.
However, due to the great varience from one reeftank to another, and the nearly infinate combinations of substrates, maintenance practices, bioloads, ect...you really can't make much general inferrence at all from their results to the hobby in general. Quite simply, their scope is far too narrow.

Now, before anybody tears into me for that last statement, let me say I'm fully aware that the logistics of performing a similar test on a scale where the results would have greater implications on the hobby as a whole. Unless you had a great deal of time and money to invest in such an experiment, it wouldn't be practical or possible. I definately can't fault them for the scale of their experiment at all. I can however recognize that the scale and scope of their experiment makes it very difficult to carry their conclusions into the hobby in general.

Ok, on the Overall Summary being misleading...

Our experiment shows no evidence for any of the espoused benefits of a plenum (reviewed by Goemans 1999) either with or without live animals in the design. Instead our results suggest that any benefits seen are a direct consequence of the presence of the sediments themselves rather than the void space beneath it.

Misleading....Yes, their evidence supports that, but only as it applies to the scope of their study...ie in a 3 gallon tank set up, maintianed, and observed over a period of time similar to that in the experiment...I think one simply can't project this evidence into the hobby as a whole...

Overall death rates were roughly twice as high in aquaria with shallow sediments as in deep sediment treatments. The highest overall death rates were seen in aquaria with shallow coarse sediments over a plenum, and the lowest death rates occurred in aquaria with a sandbed composed of deep coarse sediments. The treatments that were closest to the design aquarists employ for deep sandbed, Miracle Mud and Jaubert plenum aquaria had intermediate death rates. The shallow coarse sediment design that is closest to that used in Berlin systems had one of the highest death rates, and the deep coarse sediment design for which there is currently no accepted name had the lowest overall mortality (Fig. 10). We did not test bare bottom tanks, but the data clearly suggest that the shallower the sediment, the higher the mortality rate, and you can't get much shallower than a bare bottom tank!

Misleading, thier evidence showed no significance when dealing with mortality. They use the term "suggests"....but the facts don't "suggest" anything, other than observed mortaility in a particular set of their tanks was higher. Since it was shown that no mathematical correlation existed, one cannot infer that the substrate had anything at all to do with mortality. And because of this, the mortality observations should have been a mere side note in the summary, with qualifications concerning the lack of correlation, nothing more.

The leap from there to comparing it to a BB speaks for itself, IMO it's a totally unreasonable, unjustified, and misleading stab at that particular method of reefkeeping.

I dont really have any questions in regards to the research/study/article, It is what it is and is spelled out with in the work.

That's probably the smartest thing any of us have said about it to this point in the thread...

MikeS

 

[aquariumdebacle]

I don't think Mark Twain ever had problems with the numbers involved in statistics. He had a problem with the PEOPLE that TRY to interperet them. Let's see some of you non-PHd's come up with and experiment and defend it against people that just disagree with it from the start. At least this experiment was an attempt to quantify posssibly unqauntifiable situations. Until someone comes up with something better I am calling this the best sand bed experiment ever done.

 

[MikeS]

I don't think Mark Twain ever had problems with the numbers involved in statistics. He had a problem with the PEOPLE that TRY to interperet them.

No...., I belive he had a problem with statistical data is used to misrepresent or over generalize something. As far as my TRYING to interpet them goes, if you have found a flaw in any of my interpetations of their statistics, I'd be MORE than happy to listen to what you have to say.

Let's see some of you non-PHd's come up with and experiment and defend it against people that just disagree with it from the start.

As stated above, I don't disagree with their findings at all. I disagree with the generalizations they make from these findings in their summary. Also, I was never against it from the start, I have always been an avid defender of the DSB from the start, ask anybody...only difference now is that after talking with others whom opinions I respect, I'm begining to to look at the DSB more objectively than I did so in the past. On doing a comparible study, as I stated above, I'd never be able to perform one due to time and money that would have the scope necessary to perhaps make good inferrences to the hobby in general...however, if somebody is willing to pay the bills, I'd love to give it a try....

At least this experiment was an attempt to quantify posssibly unqauntifiable situations.

It's a good thing that people are doing research of this type.They are quite correct when they point to the lack of emperical evidence out there to support differing viewpoints concerning this matter. It does however, no longer become a good thing when inferrences beyond the scope of the experiment are made, especially, as you yourself stated, on a topic that perhaps cannot be quantified. Also, when inferrences are made on observations that the math simply doesn't support, like the mortality issue, it becomes misleading.

Until someone comes up with something better I am calling this the best sand bed experiment ever done.

Hey, you have every right to do so, you can take whatever parts you like and infer them to the hobby in general. Nobody is saying you can't. Although the thread started out in a negative light (I'm very much to blame for that), I think the point we are trying to get at is to view it, as Mike stated, for what it is. I don't think anybody is questioning the validity of their results. They have the math to prove it. What people are questioning (at least what I'm questioning) is how you interpret those results and the general inferrences made from them. Like I said above, if you can find a flaw in my interpretation of these statistics, I'd like to see it. The study says what it says. The summary and general conclusions is where I have a problem...

MikeS

 

[mojoreef]

LOL Dan and this is the standard answer when anything is ever questioned...thus why bother.

Here is another way to draw a conclusion. the deeper the sink the longer it lasts, the smaller the sink the shorter it lasts. When you have a 8 to 10 degree shift in temp, things are going to die, based on how healthy they happened to be prior to entering the tank. BB is the Great Satan ( that was for you Dan )

To be honest who is going to set up and run a tank like that?? How does it pertian to us?? If I set up a dsb tank I am going to stock it, create the best flow I can get, use mechanical filtration to help it (skimmer and so on) and I am going to control temp, ph, alk and so on.?? no??
The BB thing is kind of funny, the concept of a BB tank is to remove the waste before it becomes soluable or before it breaks down into ammonia and so on. Even if he had put a BB tank in the experiment what would it be?? a power head and call it a day??
Nothing in that study can be used by the hobbist! yet if you look at some of the other like minded experts its already being referenced to drive thier agenda.

Sorry I just have a hard time buying into this mentality


MIke

 

[clayswim]

As poorly as this study was controlled how can we possibly believe that the differences had to do with the sand anyway? It's not as though they setup 100 tanks of each kind and looked at a percentage. That might, just might, have made a difference. As Mike just said, this experiment used very few pieces of equipment that all of us would consider essential to keeping aquariums; like perhaps a heater and/or chiller for example. How much more basic can you possibly get than temperature control; especially when mortality is part of the test? All of this talk about whether the numbers are right or wrong doesn't make any difference whatsoever. Numbers mean absolutely nothing in a study if the data is tainted. I could give you numbers that mean diddly-squat to what we're actually doing and would you be impressed? I certainly hope not.

I for one refuse to follow the recommendations of a horribly run study just because nobody had ever done one like it. A lack of solid data doesn't make bad data reliable.

To argue that BB is bad for a reef is insane. There's nothing you can find throughout the vast experience people have had that would give credence to that argument. Because they killed a fish quickly in a tank that has a shallow layer of sand proves what? Although there is something to be said about the benefits of a well-stirred DSB, there are also many valid arguments against their use. As Mike pointed out, things tend to settle in water. I use settling barrels on my Koi pond because of that fact. You have the water exit the top of the barrel and the solids will sink to the bottom and stay there. You can then open a valve on the bottom to drain the sludge out. Works fantastic. Unfortunately you can't open a valve on a DSB, so you end up with waste that can't be cleaned properly. Does it breakdown eventually? Sure it does; but that isn't always a good thing. To remove it from the system quickly is surely the best method, and nothing works better for that than BB. This could very well open a can of worms, but in my mind no sludge is better than lots of sludge. For the record I use a shallow bed in my tanks, but only because I like the looks of it better and you can keep it halfway clean. The increased buffer is bound to help too.

Clayton

 

[Haole]

Thanks Mike, although many times I attribute my success thus far just as much to blind luck as to any skills I may have picked up :lol: I agree, However I wish I had known more about said limitations to begin with...I mean a few years after I put my DSB in, this kind of information began to surface more and more frequently, and I tended to blow most of it off...but as more and more of it surfaced, I could no longer totally ignore it...When I first met mojo, I had heard many of the arguements before, but he wore me down... :lol: And subsequentually forced me to re-evalutate my perception of the DSB
http://www.coralforum.com/viewtopic.php?t=1687

Well... At the very least, I got a pretty good read out of the link MikeS provided!
Thanks for sharing, O’ Dark Lord of the Sand.

 

[wave98]

Mojoreef:
I'm a noobie but gewdie. I came to RF on a link to "substrates and plenum wasting".
I viewed the thread for a couple of pages and then skipped to the "end", but the thread "actually ended" in late 2004. I have recently built a wasting plenum into my 27 gal. hex which is only 6 mos. old and have not started any "wasting" yet. back to the subject at hand - - - It seemed as if the plenum wasting thread just ended without reaching any conclusion and I haven't yet found another thread where the discussion got picked up. Is the subject dead or can you help me find the correct thread for it?

I am really impressed with the RF site and hope thar I haven't unduly interupted your current thread here.

Thanks,

Wave98

 

[wrightme43]

I dont think anyone has any new info on that thread. If you want to post to it, and see if you can get it started again that would be great. I really enjoyed it, and that was where I started with R.F. myself. I have learned alot since then and was wondering about that thread the other day myself.
Steve

 

[wave98]

plenum wasting resurrection

Wrightme43:
Thanks for the response. It seems from review the that I did in the in the original thread, that the scope of investigation on this topic was prematurely relegated to that of the "occasional wasting" permutation of this widely variable solution to nutrient and element control. It is the variability of this method that would seem to offer the most to both control and experimentation.

The many authors of posts in the original and related threads have vastly more knowledge in the area of bacteria, nitrate reduction, diffusion, etc. and I do not pretend to have very much to offer in that biological expertise arena.

I do have a lot of experience in "system optimization", however, and it appears to me that the potential of this alternative system has been left woefully under investigated.

It will be up to the biology and chemistry gurus to become reinvolved in this pusuit in order for any gains to be made without undue strictly "imperical"
and/or "seat of the pants" endeavors.

I have seen the plenum wasting alternative to seem be most potentially advantageous in a continuous or nearly continous fahion of "wasting", with "continuos" being nearly impossible based on mechanics considerations.

The "psuedo continous" version (at least several times a day ) appears to be readily doable on an engineering basis, so long as we can obtain enough information from the chemistry gurus to start out at least in the right general direction.

This would appear to require a "wasting rate" that would support a viable bethnic zone at the substrate surface and support valuable functions of the upper aerobic zone, while allowing an anoxic and/or anaerobic zone thereunder for a distance that would be supportive of diffusion back to the surface, if possible.

Beyond this, we are in the zone of controversy ( and danger )
regarding sulfides and god knows how many other disastrous compounds, but this is the beauty of the "continously wasting plenum" which will remvoe these hazardous compounds in a "one-way" fashion from the vicinity of our "beloved charges".

I do not know if the participants in this earllier discussion had become concerned about "homogenous movement" of the "wasting water column" or not, but this would be the area that I think is the least of any mechanical problems associated with the concept.

Mojoreef:

I am hoping for some response on this subject, and would be happy to start a new thread for this discussion, hoping for a little bit of response and evauation from the biological and chemical gurus.

I surely hope that this post has not aggravated anyone over bringing up a dead(?) issue, and look forward to reopening a door to more reliable and consistent reefkeeping.

Thanks and "happy reefing"

Wave98

 

[wrightme43]

Hey Glad your here. Hardly anybody here ever gets upset. With the exception of me and a few others. I am getting better about it though. LOL
I am sure if you start a thread it will be well recieved, some people may argue but its all in the pursuit of bettering the hobby. Most people who like to flame and fight dont stick around here very long. Baseless arguments are usually just handled with facts. I know I cant speak for everyone, though I am very proud to be a part of R.F. and friends with most of the people here. Please keep coming back.
Steve

 

[mojoreef]

Wave great to see you jump on board and welcoe to RF. WHy dont you start a new thread and then just copy and paste the thread you just posted that way we can give this topic the attention it deserves


Mike

 

[Elmo18]

I still like my sand

- Elmo

 

[Witfull]

I don't think Mark Twain ever had problems with the numbers involved in statistics. He had a problem with the PEOPLE that TRY to interperet them.

ther problem i see is that anyone can take a handfull of stats and list them in such away that it validates their conclusion. i agree that their is an agenda out there....and the conclusion has already been written and all that needs to be done is work backwards to make things fit.

over the past 2 yrs i have seen so many "knowedgable" people overtly pushing and defending DSB's and on the same hand trashing the idea of BB as oldschool,,,revisited and without improvement doomed to repeat its original failure. here is just one for example
http://www.reefkeeping.com/issues/2004-10/eb/index.php

It is perhaps ironic that the methods developed for successful reef mesocosms by Adey (1983) had already promoted and utilized deep sand beds, that the "Jaubert method" (Jaubert 1989) strictly depended on the use of heavy carbonate beds, that Julian Sprung wrote about his successful application of Jaubert-based tanks in the early 1990s, and that I established my first pure Jaubert system in 1994 to great success for many years, and continued to run (even today) tanks filtered naturally without the use of skimmers. In the early 1990s, people "pulled the plug" on their wet-dry filters. In the mid-1990s, some people began pulling the plug on their skimmers and adding deep sand beds. Now, it seems people are pulling the plug on their sand beds and going back to heavy skimming and bare bottoms - a fifteen year old method whose inadequacies were the cause of the bare bottom demise in the first place.... What's wrong with this picture? Why would aquarists suddenly begin removing sand beds given their useful function in many regards? I cannot answer in every case, but it seems as though a lot of it is the same herd mentality that caused the addition of sand beds in the first place (the difference, of course, being that the sand bed addition was a good idea!).

it continues to blame the reefkeeper for the DSB failure, which is partly correct,,but was it really the reefer that failed or them believing what they were sold,,,"set it and for get it."

and to add a little humor to the end of this,,,,statisically speaking, the average person has one breast and one testicle.

 

[Witfull]

PS....i fell off a log once,,,hurt my head

 

[wrightme43]

Hey Wit, glad to see you. We miss you. I mean people are talking about crabs. LOL

 

[wave98]

It seems that there is more than one "agenda out there". A lot of people are trying to promote "their majic bullet". It is rarely "theirs" to begin with for one thing, and reef animals don't live in "majic bullets" either! :idea:

But "boy" can people become proud of the "intelligent decision that they made", and then heaven forbid "disdainful" of those who have not "jumped on the "bandwagon".

Then the "skew" and the "spin" starts, and continues. Right after that comes the "backlash", and the "reverse spin". I think the reverse spin is the worst! :badgrin:

Lets see, Dsb, BB, Plenum, UV, Skimming, "Goldfish VS SPS", whatever.

The average person, also has one brain, and Thank God most average people don't get into reef keeping! :lol:

Happy reef keeping > Wave98

ooPS! You know, I met a person once that had two brains, and one was looking for the other! I don't know how that turned out, I couldn't find him again.