It's Still in the Water!

Habib:

So are you saying that we only have a need to be concerned with free copper or free metals? Don't you think there is reason for concern about the other 99.9%?

Here is an article specifically regarding pollution in San Diego Bay.

http://www.tsrtp.ucdavis.edu/newsletters/fall_2000/IndicatorsofPollution.html

It opens as follows:

Ocean pollution is a serious environmental concern, especially in developed coastal areas where shoreline and bay sediments may become reservoirs of urban and industrial pollutants, including heavy metals, As a consequence, organisms living in or on the sediment, or those that prey upon bottom-living organisms, face heavy-metal exposure.
Click to expand...

I have a DSB and animals that eat those critters that wallow in those sediments. It looks like oceanographers are concerned. It looks like invert. biologists are concerned. Why shouldn't I be concerned, especially if the concentrations in my tank are much higher than in the San Diego Bay?

Just curious,
 
Ron,

Previously in this thread you suggested that water changes are not effective in controlling "trace element" levels due to the food we add increase the levels faster than any sane water change regime could cover for (I think that's what you meant by referring me to your April article ??).

If this is the case then the starting point, no matter whether we use this trace element free salt or any of the normal artificial salts, is equally irrelevant? Or have I missed your point?
 
Hi Andy,

I probably didn't explain it clearly.

As long as we are using salt mixes that have exceptionally high levels of trace metals, water changes are futile, the best we can do is get back to the original very level from an even higher level (after feeding).

If we can use salt with low trace metal concentrations, we can lower the metal concentration significantly and keep it under control. The key is that we need salt that is not loaded with these materials because, among other things, we add them each time we feed.

At the time I wrote the April article, I didn't know of any salt that had low trace metal concentrations or I surely would have tried to explain it better.

Sorry for the garble, and hope this helps.

:D
 
Thanks Ron,

However I think you were right first time (even if you didn't mean to be :) ). In your article you wrote:

These concentrations are sufficiently high that if these materials were all converted to soluble form, the water volume of the tank would receive enough of them to be raised from zero to around NSW levels, EACH DAY, EVERY DAY.
Click to expand...

So what if "Mr Salty's Poison UR Tank salt (TM)" is x7 NSW on day 1? Give it a month and the difference between the "pure" and old Mr. Salty's will be trivial. The feeding input is such a massive influence vs. the starting point that I really can't see it matters greatly. Change 100% of the water and you've only bought yourself potentially 2 days grace before you are once again double NSW (ok not all of the elements will enter the water column for some reason, but the principle remains).

I still believe the method of control lies in tank water filtration (if indeed we are looking in the right area for the causes of OTS, which to a greater or lesser degree I do, certainly my corals have a growth spurt after a 50% water change). If "pure" salt is available for an equivalent cost as the normal stuff then why not I guess. It is certainly of some benefit. Probably the most important factor (to my mind) is designing the system such that large (>= 50% water changes) can be performed with ease (therefore done!), anything above and beyond that is a bonus.

YMMV :D
 
rshimek said:
Another point as well, if these chelators are being produced by the all of these algae and bacteria, do you not start to wonder why? Simply put it is because the trace metals are damnably toxic to them, too and this is there way of getting rid of them.
Click to expand...

You go Doc! Hammer it home. :hammer:

IF these chelators are being produced then it is a defensive response to the toxins.

Humans have been poisoning themselves by smoking tobacco for years and survived and some have even managed to reproduce (although with some birth defects), but you wouldn't tell your children today that there's nothing wrong with smoking would you? "Hey, go ahead junior, light up! It won't kill you (cough, cough, hack) and your body will naturally cough up the phlegm in the morning to protect itself! No problem!"

Now that I know the toxins are there I feel a moral obligation to remove them for the sake of my captive organisms.

Instant Karma's gonna get you... :dance:
 
So, the question - in I hope a non-confrontational mode - is why add iron? At best, you drive algae, at worst, you drive cyanobacters.

It has helped algae in many tanks. This effect can be seen instantly (well, in a day or so) after adding iron to tanks with certain macroalgae getting pale and not growing well. THey quickly green up, grow faster, and hence remove more nutrients like phosphorus.

Also, my survey shows that it may help in prevent what people refer to the sexual reproduction phase of caulerpa. The statistical significance was high enough to make this worth trying for people who've had the problem.

FWIW, my article on iron detailing all of these things shold post any minute now.

IF these chelators are being produced then it is a defensive response to the toxins.

In some cases, yes. In other cases, it is because the organisms WANT the metals, and are scavenging for them. This is especially true for iron, but may hold for many other metals. If they are not getting enough metal, they relase more chelators. There is a long thread about this and a paper that Tatu posted in my forum.

In other cases, it is entirely coincindental that the organics bind metals, as their intent was something entirely different (for example, bacteria surface themselves bind heavy metals). So dead bacteria parts will bind metals.

Now that I know the toxins are there I feel a moral obligation to remove them for the sake of my captive organisms.

Unfortunately, there is no good way to do that (that I've heard). Polyfilters are a sledgehammer that bind many metals, including some that I don't want bound (like iron). They also will not bind chelated metals to any significant extent. And they will not bind sediments that are either microscopic or macroscopic.

Salts with lower trace metals? I'll believe that when I see a tank running for a few months with such a salt and that maintains the low levels. Remember, it's not just the salt mixes to worry about. It's the calcium supplements, alkalinity supplements, metal devices in the tank, etc. etc.

If "pure" salt is available for an equivalent cost as the normal stuff then why not I guess.

That if seems pretty large to me. I don't see how it is even remotely possible. Were talking about ppb concentrations for some things.

I have a DSB and animals that eat those critters that wallow in those sediments. It looks like oceanographers are concerned. It looks like invert. biologists are concerned. Why shouldn't I be concerned, especially if the concentrations in my tank are much higher than in the San Diego Bay?

But Ron is comparing tank water to ocean water, and comparing tank water to known toxic levels for metals in water. Not tank sediments to Sand Diego bay sediments. Habib's concern is that Ron's test may have included sediments in the tank water test. Microfiltration only gets down so far.
 
Randy has pointed out he cannot test for this. Interestingly enough, then he cannot propose a testable or falsifiable hypothesis.Given that testable hypothesis cannot be formed, he (we, they) have to take this explanation without any sort of verification by the scientific method, which requires testable hypotheses.

So, we have an explanation of events based on documentation in dissimilar systems which must be taken on faith, and on the word of a true believer.

Sounds to me like you guys are creating a religion; The Cult Of
The Totipotent Chelator.

When and if you can use the scientific method to show that this has any effect in tanks I will be glad to hear about it. 'Till then...

Please, I'll speak for myself. It is not hard to design a proper experiment in this case. If you spent more time thinking about the issue and less thinking up witty ways to make fun of people's ideas, you might have thought of it yourself.

Put free metals in artificial seawater (or whatever is preferred for toxicology tests) to the total metal concentrations found in tanks. If both waters (tank and artificial + metals) are equally toxic and substantially more toxic than the artificial seawater alone, then the binding to organics is unimportant for toxicity.

OTOH, if the toxicity of the tank water is lower than the artificial seawater plus the metals, then orgnaics may well be the explanation (though there are others, such as particulates being measured in tank water that are not toxic). In any case, it will show whether ICP measurements are appropriate for determining the metal toxicity of tank water samples.

To be perfectly honest, I'm not claiming that metals are toxic in our tanks, or not. I've said so several times. They might be. They might not be at the levels found in most tanks. As per the scientific method, however, I'm pointing out other possibilities that had not been considered in coming up with the conclusion that we are "killing corals". FWIW, you make it very hard for people to keep a middle ground position because you present your opinions as conclusive facts, and that leaves some of us to point out other opinions that may be true, or may not be true, but that have not been ruled out by any existing data.
 
If there is so much organic chelation going on why should we worry about heavy metals pollution of the ocean and the world's reefs?

It sounds like the metals should be quickly bound up and not pose a threat in any environmental system.

Obviously not, or the various organisms would not spend the energy to make organic compounds to detoxify their environments.


Two concerns:

1. The organics in our tanks may be far higher than in the ocean, so the toxicity may be much lower. After all, the relative concentration of the creatures that release organics is higher in our tanks, so it makes sense that their products would also be higher. I have no data, however, on the concentrations of any specific organic in our tanks.

2. The metals in the ocean may be far less toxic because of binding to organics. Maybe the problem would be 10,000 times worse if not for the organics. So the fact that there is or is not a problem says nothing about the role (if any) that organics play.

If we want to get into talking about contaminants in sediments (where the environmental problem often lies), that is well worth discussion. We have, however, no data on sediment pollutants in reef tanks.

I'd also point out that pollution with organics is just as pervasive and problematic as pollution with metals. GE is being forced to dredge the Hudson to take PCB's out of the sediments. PCB's are organic! So by all rights we should be just as concerned about organics as metals. Unfortuantely, analysis of organics is far, far more complicated than ICP.
 
Ron,


These tests were run exactly as standard pollution monitoring tests are run. The data are compared in exactly the same manner with the same conclusions being reached.

If the tests show that levels of a certain metal kill animals, and if the tests show that the levels are above those levels, and animals do die then it is reasonable to suggest that the metal is responsible. It really doesn't matter the type of ion that is involved

Many hobbyists are running tests by having one or more aquarium, keeping corals, growing them, multiplying them,...

They are alive. With they I also mean the corals and not only the aquarists in case that is not clear enough.
Now if the elements present in the average aquarium are toxic at the levels you measured of these average (random) aquaria within which period of time should the corals die? a few days, a few weeks.

If you answer this remember what you have said in previous posts.



Sure you did. Yup. Somewher you have those data....

Now lets see them published somewhere.

As a matter of fact I have recently been invited for an article........



From your respons to Randy :

We do know that concentrations of the chemicals seen our systems can cause toxic effects. We do know that they even if such metals are rendered temporarily insoluble that minor changes of condition can make them soluble and toxic.

So what you said is that metals are rendered temporarily insoluble then change of condition can make them soluble and toxic.

So according to you if it can not be made soluble it is not toxic.
That is being not bio-available. Is this what you are saying or do you diasagree with the scientific community?

BTW EPA recognizes/accepts that toxicity of an element depends on the speciation and how it is present.
It is generally accepted that speciation etc. determines the toxicity, bioavailability , bioaccumulation,...



With respect to the data of copper speciation in san diego bay posted by me you said:

Which simply means it gets eaten by something and kills them during digestion rather than by epidermal absorption.

If this is no speculation then show us the data for the above concentrations and speciation.

Sounds to me like you guys are creating a religion; The Cult Of The Totipotent Chelator.


Sounds to me as an insult. Or is it because my knowledge of the English language is so poor. Please explain.
 
Bomber:

Wouldn't acid meet that requirement?

Considering the very low solubilty products of heavy metal carbonates and oxides it would require a pH far below necessary to dissolve calciumcarbonate. So the system will resist low enough pH concentrations being reached as long as calciumcarbonate is present.

Furthermore natural seawater and aquariumwater have a pH buffering effect thanks to the bicarbonate/carbonate (carbonate alkalinity) system.

Furthermore the solubilty products for inorganic particulate matter will be even much lower than the values obtained in seawater free from organics.

These particles are covered rapidly by many organics, decreasing the solubility product tremendously.

Also thanks to the above mentioned at least some aquatic organisms are able to secrete a skeleton (bio-mineralization) which resists dissolution or atleast transformation of their crystalstructure. Without these organics they might dissolve.
 
Ron,

After you are done with replying to the above posts here is something more.

It is a description of EPA Grant Number: R825220 ;
Biogeochemical Control of Heavy Metal Speciation and Bioavailability in Contaminated Marine Sediments


EPA Grant Number: R825220
Title: Biogeochemical Control of Heavy Metal Speciation and Bioavailability in Contaminated Marine Sediments
Investigators: Shine, James P.
Institution: Harvard University
EPA Project Officer: Manty, Dale
Project Period: December 2, 1996 through December 1, 2001
Project Amount: $453,630
Research Category: Early Career Awards


Description:
The total concentrations of contaminants in an environmental sample are not indicative of the potential for adverse ecological effects. Contaminant speciation and its effect on bioavailability are critical to understanding ecotoxicology. This information is also crucial for development of policies concerning the use and disposal of toxic material in the environment.
An initiative is currently under way at the national level to understand the factors controlling the toxicity of heavy metals in aquatic sediments. Heavy metals discharged into aquatic ecosystems are likely to be scavenged by particles and removed to the sediments, perhaps leading to a situation where the water is ?clean' yet the underlying sediments have accumulated toxic levels of heavy metals with resultant adverse effects on ecosystem health. The presence of sulfides and particulate organic carbon have been appropriately identified as factors buffering the availability of heavy metals in contaminated sediments. However, even when the ability of these constituents to buffer the toxicity of metals is exhausted, toxicity is not always observed. This implies other binding phases which may also contribute to reduction of metal availability in sediments. These other binding phases may include dissolved and colloidal organic matter in porewaters which can form stable complexes with heavy metals, thus reducing their bioavailability.

The proposed work will examine the role of dissolved and colloidal organic matter on metal speciation and bioavailability in marine sediments. Speciation will be measured at two contaminated locations in New Bedford Harbor, USA, and at a comparison ?clean' location in Buzzards Bay. Observations will be made over multiple seasons to observe temporal and spatial variability these ligands have on metal speciation and bioavailability.

The specific objectives of this proposal are as follows:

1. Develop methods to determine the role of dissolved and colloidal organic ligands on the partitioning of metals between particles and pore water in marine sediments and observe how partitioning varies in space and time.

2. Determine, in conjunction with acid volatile sulfides, how adsorbed (particle bound) and porewater ligands control the availability of heavy metals to transplanted and native benthic organisms.

3. Develop methods to quantify the thermodynamic characteristics of adsorbed and porewater metal binding ligands.

4. Develop the study findings in a framework that assists development of criteria for protection of aquatic ecosystems.




Please explain to me if a certain concentration of metal is determined without discriminating the speciation etc. , that is in the way your measurements were conducted, then how you could deduct the speciation from just these data?

If that can not be deducted , and it can not be deducted, then nothing can be said about the toxicity or any inhibition effects.

Or do you disagree that speciation etc. of a metal affects toxicity? If so show us any as recent as possible reference or any data which would support your disagreement.

But on the other hand if you agree then how can you say anything about the toxicity of the metals found in the measured concentrations without knowing speciation etc ?


From your last Reefkeeping magazine article:


The literature on the effects of these chemicals, specifically, Cadmium, Copper, Chromium, Lead, Mercury, Nickel, Vanadium, and Zinc, is rather depressing, frankly. It deals with nothing more than mortality factors or how the organisms deal, perhaps more importantly, how they cannot deal, with enhanced levels of the chemicals.

I suggest you do a better literature search. Many enzymes will not function without heavy metals. Without them no corals, no coralline algae, no bacteria, no..........


Another thing:
If toxicity takes place then it automatically means that the metal which is causing toxicity is taken in by whatever pathway by that organism.
If that happens the metal is bio-available. In such situations relatively huge amounts of that metal will be taken in until the organism dies or the pathways of toxic metal intake have ceased to function (almost dead).

Now if the metal is that much bio-available to be toxic then how come there is still that metal present in the water column (limited volume)?

It should be used up quickly and become undetectable by your methods if it were toxic and therefore bio-available. Isn't it???

And why there was no iron detectable in the aquariums you tested while all sea salts tested have a large amount of iron in them and there were other metals such as copper (which you consider to be toxic) still present in a concentration similar to what is present in saltmixes?
 
Originally posted by Randy Holmes-Farley
Click to expand...

Please, I'll speak for myself. It is not hard to design a proper experiment in this case. If you spent more time thinking about the issue and less thinking up witty ways to make fun of people's ideas, you might have thought of it yourself.

I did, but I think the issue is unimportant. You seem to think it is important, but seem totally unable to present any data from aquaria supporting your position. Basically, you are "jumping up and down and waving your arms, " but don't seem to be willing or able to do the work.

I have pulled together a short reseach project over the last few years, showing the absurd levels of poisons in our tanks and the paths they take through our systems. I started with the sea water composition work by Atkinson and Bingman and
  • Working through the foods added to our systems,
  • the amounts of poisonous trace metals in our tanks water
  • what is being exported (the data are on hand and will be published this autumn) and
  • the toxicity of various waters to standard test.

It seems to me that if you thought that organic materials had some real effect in our systems, you could do the work to show those effects.

Basically, Randy, put up or shut up; all you have said is simple conjecture.

If we want to get into talking about contaminants in sediments (where the environmental problem often lies), that is well worth discussion. We have, however, no data on sediment pollutants in reef tanks.

I will - if I can get the $$ - be examining the metals in tank sediments late this autumn as one of the upcoming components of the this project of mine.

Perhaps you should undertake some research about the organic components, if you think they are important.

Habib
Click to expand...

Considering the very low solubilty products of heavy metal carbonates and oxides it would require a pH far below necessary to dissolve calciumcarbonate. So the system will resist low enough pH concentrations being reached as long as calciumcarbonate is present.

The system will resist this, true enough, but these materials will still be toxic to organisms as they will encounter sufficiently low pH values during digestion. Many aquarium animals, including corals ingest and digest particulate material, additionally much fine particulate material - including potentially toxic material- is moved from tank sediments or the surface of live rock into the water where suspension-feeding animals will encounter it. The animals will convert this insoluble - and harmless - material into a toxic material within their body.

If that can not be deducted , and it can not be deducted, then nothing can be said about the toxicity or any inhibition effects.

Certainly, it can. In the same way, observational/correlative research is done. If the level of a certain chemical is measured in the same way it has been measured elsewhere, and if mortality has been associated with those measurements elsewhere, then the mortality may correlated with the measured value.

This does not imply direct cause. However, if such a correlation exists then there is certainly reason to suspect the measured factor is having an effect.

The "species" of the metal is unimportant. What is important is that every time the metal is measured at, or exceeds certain values, mortality occurs. It may well be due to the form of the metal in the solution, or to the form that the organism converts it to. However, it happens, the metal is toxic.

suggest you do a better literature search. Many enzymes will not function without heavy metals. Without them no corals, no coralline algae, no bacteria, no..........

Read the statement in the article again, and don't take it out of context. In the context of the article I was referring to the environmental physiology of these materials, and the statement is correct.

Certainly, in natural trace amounts these materials are necessary. Neither in the environmental literature nor in our aquaria are these materials at anything near natural trace amounts.

If toxicity takes place then it automatically means that the metal which is causing toxicity is taken in by whatever pathway by that organism.
If that happens the metal is bio-available. In such situations relatively huge amounts of that metal will be taken in until the organism dies or the pathways of toxic metal intake have ceased to function (almost dead).

This is absolutely incorrect. The material may be ingested in an non-toxic form and converted to a toxic form within the animal. Happens all the time....

And why there was no iron detectable in the aquariums you tested while all sea salts tested have a large amount of iron in them and there were other metals such as copper (which you consider to be toxic) still present in a concentration similar to what is present in saltmixes?

The test method is rather insensitive to iron. But more to the point, iron hydroxides have been shown to complex with some of the trace metals, and I suspect it is bound that way and removed from solution. Also, iron is preferentially taken up by cyanobacteria and some algae, so the concentration of iron is probably lowered biologically.

Copper is not taken up preferentially by any animal. I do consider it toxic, copper kills animals... and algae.... and bacteria. Maybe this isn't toxic by your definition, but it surely is by mine.

I am glad you will finally publish some results. Regardless of the result, at least you seem to have been doing some research, unlike other posters.
 
Do you think testing "substrate" for metals will yeild any information that conclusions will be drawn from?

In general, toxicologists consider what is in sediment as an indicator of overall health of a system, nothing more. And, in light of that, would you be looking at pore water samples, overall water, sediment? I think each has relevance and in order to draw any real conclusions, I think we would need to see each piece of that puzzle. I believe this is especially important in light of the fact that the only mechanism in our tanks of moving a toxicant from one region to another is via biology. If the organisms are consuming the sedimentary organics and re-releasing those as larvae.
 
Hi Wade,

If I get around to doing this I will look at the sediment proper, basically to find out the metals levels are. I don't want to get into sampling pore water, etc. Simply put, at this time it isn't worth the money for me to do this, as all of this work has been either self-funded or funded with the help of some aquarists, money really is a driving force.
:D
 
andy-hipkiss said:
Ron,

Previously in this thread you suggested that water changes are not effective in controlling "trace element" levels due to the food we add increase the levels faster than any sane water change regime could cover for (I think that's what you meant by referring me to your April article ??).

If this is the case then the starting point, no matter whether we use this trace element free salt or any of the normal artificial salts, is equally irrelevant? Or have I missed your point?
Click to expand...

I don't think you missed the point at all. And after finding a better salt mix the focus will likely turn to finding or culturing cleaner foods. There are encouraging possibilities...

Check out this thread...
http://www.reefcentral.com/vbulletin/showthread.php?s=&postid=726769#post726769

I've gotta admit I'm surprised this thread has dragged on the way it has. The metals are present in our aquariums in amounts far above natural levels. Getting our tanks closer to natural levels where feasible is a worthwhile and logical goal.
 
Basically, Randy, put up or shut up; all you have said is simple conjecture.

Conjecture? That's a laugh. Doesn't the fact that thousands of people have reef tanks growing corals at rates similar to natural growth rates in "absurd levels of poisons" seem to suggest that it is your theory about toxicity, and not my theory about why people have been successful that is most lacking in evidence? Actually, I won't ask you the question. I'll state it: yes, it does suggest that there is a problem with the theory that we are killing corals. It is not conjecture that these corals do fine. It is conjecture that some are being killed.

Can you show even one coral from anywhere in the world that died in a reef tank from metal poisoning? I thought not.

Remember, you have absolutely zero real toxicity data in reef tanks. You ridicule me because I don't have data on organic levels, but you don't have any tox data.


Perhaps you should undertake some research about the organic components, if you think they are important.

That doesn't sound like a scientific suggestion, but more like a way to make me sound uninformed or uninterested in helping the hobby. What if I told you the levels of 3,215 different organics, 256 of which are bound to 25 different metals in my reef tank? What would that do for anyone? Total squat, that's what. Then you'd simply say, OK you've shown nothing that says anything about toxicity of metals. It all boils down to toxicity tests if toxicity is the claim. Running such a test in reef tank water is as easy as running one in low metal seawater. Most scientists would run such a test before claiming that we are killing corals. Since you made the claim, it is incumbent on you to back up the assertion, not on your critics to "prove" you wrong.

I've gotta admit I'm surprised this thread has dragged on the way it has. The metals are present in our aquariums in amounts far above natural levels. Getting our tanks closer to natural levels where feasible is a worthwhile and logical goal.

I'm sure we'd all like to see what happens when that is done. Can it be done? That remains to be established for anything short of a reef tank for Bill Gates. Even so, let's see what happens. Then we can really see the merits.

The animals will convert this insoluble - and harmless - material into a toxic material within their body.

Yes, that could very well be, to some extent, but it isn't appropriate to extrapolate the toxicity of such materials from the toxicity of free metal ions. Suppose the real toxicity level of such particulates was slightly, or greatly, higher than the tank concentration? Aluminum ions are quite toxic, aluminum oxide is not, even when passed through the low pH stomach of humans. One cannot quantitatively equate them.

Neither in the environmental literature nor in our aquaria are these materials at anything near natural trace amounts.

Of course, that may not be true of all ions that we are concerned with. Did you detect any iron? In fact, I recall many ions that you did not detect, and some are necessary nutrients. Don't tell me that you want to lower those too, even without knowing what the levels are?

Copper is not taken up preferentially by any animal.

Another incorrect generalization. It is preferentially taken up in humans. Ever hear of Wilson's disease? Since you didn't apparently know that even about yourself, can I assume that you aren't sure about every single one of the 5,234 organisms living in my reef tank?

I am glad you will finally publish some results. Regardless of the result, at least you seem to have been doing some research, unlike other posters.

Ahhh, such a cutting blow. How can I even hope to have a scientific discussion when I'm burdened with such guilt over leaving toxicity studies to you? Oh, I forgot, you haven't run any either.
 
Originally posted by Randy Holmes-Farley
Click to expand...


Oh, I forgot, you haven't run any either.

Ah, yes... but they are scheduled.

And as for your efforts - - - have you done any studies at all, Randy? Have you generated any aquarium data, at all, that support your ramblings? Any supporting data whatsoever for your conjectures? Or, perhaps better put, any supporting data for your "unsupported guesses?"

.

.

.

.

I thought not.
 
I am sure that Ron and Randy are having fun with this manhood swinging contest but I have a somewhat off the immediate topic question. I will first say that I am not a Biologist or Chemist, I am a CPA and therefore a complete idoit when it comes to biology or chemistry (I had to read the article and thread several times to follow it). My question for Dr. Ron has to do with sample size. I have read the article (and previous Reefkeeping magazine articles you have written) and as far as I can see your sample size for these experiments is 23 aquarium water samples. Is a statistical sample size of 23 adequate to draw conclusions about the population as a whole? I am not exactly sure how many reeftanks there are in the world but I would dare say that your sample is less than 1/10th of 1% at best. If I am incorrect about your sample size please accept my appology in advance.

As my disclaimer I am not trying to throw my manhood in on this I am just curious about your sample size as it relates to the total number of reeftanks. My remarks are not intended to insult, insinuate, irridate, annoy, etc. There that should keep me from getting flamed :D
 
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