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Joshua Levy's Review of Dynamic Aquaria


  1. My Review of Dynamic Aquaria (part 1)
    by (Joshua Levy) (27 Oct 1994)

My Review of Dynamic Aquaria (part 1)

by (Joshua Levy)
Date: 27 Oct 1994
Newsgroup: rec.aquaria

A Review of Dyamic Aquaria
Part I: The Content of the Book

Joshua Levy
(San Francisco Aquarium Society, American Livebearer Association)

The Reviewer's Background: I keep freshwater aquariums.  Low tech tanks 
which I use to keep relatively undemanding livebearers.  This gives me a 
rarther different outlook on Dynamic Aquaria (DA) than most people who have 
read and reviewed it.  They tend to be salt water or reef aquarists.  
But Dynamic Aquaria claims to apply to fresh and saltwater tanks, so it 
seems fitting to have at least one freshwater fishkeeper reivew it.

The Reviewer's Modivation: Salt water or reef aquarists have an obvious 
reason to be interested in new filtering techques.  They can breed only 
a very species, and still have great touble keeping their aquariums 
going.  Even when successful, the cost is high, hundreds of dollars per 
tank.  But I keep livebearers.  Almost every fish in that family has been 
bread by hobbists.  My tanks cost only a couple of dozen dollars apiece; 
so on the surface I have no need for better filtering technology.  But, 
DA represents the first new base idea in filtering aquariums in 20 years 
or more (algae vs. bacteria), and is therefore interesting to me.  Although 
I do not need it, I may want it, if it is better (in an important way) 
than the bacterial filters I use today.

My review of Dyamic Aquaria (DA) is divided into three sections: content, 
form, and summary.

As described above, I am not primarily interested in ecological 
simulation, but in scrubber filters.  Therefore, the content of this book 
can be measured by how well three questions are answered:

1. How does a scrubber work.
The working of a scrubber were described pretty well.  
2. Are algae scrubbers the best way to filter an aquarium? 
Although the fact that algal scrubbers are the best way to filter an 
aquarium was repeated many times, the actual evidence that this was true 
was not strongly presented.  Three pieces of evidence were presented, 

A. Geologic Carbon Buildup
DA points out that over geologic time, carbon has slowly been accumulating 
in mineral sources (example: oil).  this suggests that most biological 
filtering is done by plants, not bacteria, since it is plants that form 
these deposits.

B. Biomass size
DA also contains data showing that, as measured in biomass, bacteria are 
a small part of an ecosystem.  Unimportant is implied by small.

C. Successful examples
The book also contains several examples of successfully using scrubbers 
on a wide variety of ecosystems, including about half a dozen aquariums 
(ie. less than 1000 gallons of water).  Althought none of the aquariums 
are described completely, data is presented whch shows low levels of 
nitrites and nitrates in these tanks.  The growth a crab is extensively 
documented in a saltwater tank, etc.

These arguments are not strongly presented, and several obvious objections 
are not addressed.  Specifically, even if nature uses algal filtering, that 
does not mean it is the best way to filter aquariums.  The biomass argument 
assumes that size == importance.  But that not universally true.  Try telling 
someone with AIDS that they only have 1 gram of HIV in their body which weighs 
tens of thousands of grams, so the HIV is not important.  The successful 
examples are good, but there are no experiments comparing scrubbed tanks, to 
conventionally filtered tanks, or to unfiltered tanks. loading.

This last point brings up an interesting question.  In those places where DA 
compares scrubbed tanks to anything, they are compared to the real world 
habitat the tank is modeled on.  This makes sence from an ecological modelling 
point of view, but it does not help determine how effective scrubbers are 
at filtering.  DA compares scrubbed tanks to the ecological communities 
they are simulating.  This makes a lot of sense, from a modeling point of 
view.  From a filtering point of view, however, it would be great to do a 
filter vs. scrubber comparison.

The whole books assumes that scrubbers are a good thing, however, and showing 
this is true is not a priority.

3. How is a scrubber constructed and used?

Although scrubbers construction is described from a scientific point of view, 
it is not described from an engineering point of view.  By that, I mean  
the important priciples used in scrubber construction are described, but 
exact construction steps are not.  No plans for any scrubbers are provided.

The situation is a little better for ongoing maintenance of an operating 
scrubbers, which is described in a fair amount of detail.
By these criteria, the book is not successful.  Why algae scrubbers work 
is described, although not very well.  The fact that algae scrubbers are 
the best way to filter an aquarium is stated several times, but the evidince 
to back up this statement is thin (at best).  Step by step instructions on 
how to build a scrubber are not provided, and while general pricipals are 
documented, details are not.  And if there is one thing I've learned about 
aquariums it is that details are important!

Very little of DA is actually about scrubbers.  It is a 600 page book, in 
which I found about 40 really useful pages, and less than 40 more semi-useful 
pages.  Most of the book is about building model ecosystems.

From: (Joshua Levy)
Newsgroups: rec.aquaria
Subject: My Review of Dynamic Aquaria (part 2)
Date: 27 Oct 1994 17:19:12 -0700
Organization: VERITAS Software Corp., Santa Clara  CA
Lines: 119
Message-ID: <38pg20$>

A Review of Dyamic Aquaria
Part II: The Form of the Book

Joshua Levy
(San Francisco Aquarium Society, American Livebearer Association)

The reviewer's background and modivations are described in part I.

This second part is about the form of Dynamic Aquaria.  Unfortunately, the 
form is not that good.  DA has a very basic problem: it seems to be written 
for three different audiances, and therefore is well targeted at none.  The 
three targets are biology students, aquarium curators, and hobbiests.  (The 
back flap claims it is also targeted at fisheries biologists, but I saw no 
evidence of that.  In fact, the fish only environments which they tend to 
operate were never discussed in the book.  This was too bad, since many 
hobbiests would have been interested in scrubbing all fish tanks, as well.)

Chapters 2-11 are clearly targeted at biology students.  They contain lots 
and lots of infomration; the kind of stuff that biology students are forced 
to memorize.  There is little of interest to a practicle aquarist.  A fair 
amount of space is taken up describing how to build 20,000 gallon displays, 
which is also of little use to home aquarists.

Chapters 13-20 are targeted at micro/mesocosm builders, with little of 
interest to the aquarist.  For example, chapter 19 "Detritus and 
Detritivores" covers an area typically ignored by fishkeepers, yet 
this chapter will not change that.  It is 40 pages long, almost all of 
which is a catalog describing the various different creachers found in 
the mud of various different ecosystems.  There is also some discussion 
of how these creaters interact with each other.  At the end of this 
chapter are 5 pages on detritus in ecosystems and 3 pages of detritus 
in aquariums.  These are the only parts of the chapter likely to be 
directly useful to hobbiests.  As a freshwater aquariust, a reader will 
end up slogging though 40 pages to get 3 pages of useful information.  
Not a good yield.

This confusioin as to who the book was written for shows up in other ways as 
well.  Perhaps the most annoing is what is explained and what is assumed.  
The book uses many specialized terms from biology and ecology (example: 
"benthic"), which it never defines.  From this point of view it seens 
to be a biology text book targeted at upper class biology majors.  Students 
in such classes would be familiar with all these terms.  However, the book 
is also crowded with introductory biology material.  Basic stuff like the 
kreb cycle, respiration, etc.  This is the stuff you would expect in a book 
targeted at hobbiests, who may not have taken any collage biology.  (This 
situation is made worse by the fact that the Kreb cycle information is not 
used in the rest of the book, which brings up the question of why it was 
included at all.  There is a lot of material in this book which is 
presented in depth, for unclear reasons, and then never refered to again.)

The confusion about DA's target audiance shows up in the way measurement 
units are handled.  Fishkeepers uniformly measure nitrates and nitrites in 
terms of ppm.  When we talk about light we use lux or lumens. DA does not.  
They measure nitrates and nitrites in uMs (which I assum are micro Moles).  
I'm pretty sure the book describes uMs and why they are used, but after 
reading the book, I could not go back and find this text.  For light, they 
use mini eistiens, which is pretty useless, since data on lights is typically 
presented in lux or lumens.  Micro moles and mini eistiens give the book a 
very scientific tone, but hobbists have no "feel" for these units.  What 
does 7 uM of nitrates and nitrites really mean, anyway?

There is collateral problem caused by the units, too.  Many of the graphs and 
tables are taken from other sources, and some of them use the more common ppm 
or lux/lumen measurements.  You need to be a careful reader to make sure
the units have not been changed on you.

Another problem is the author's fondness for starting at the very 
beginning.  The chapter on temputrature, for example starts like this: 
"The average tempurature of the Universe is -235 C."  The whole 
first paragraph talks about space and stars, and whole planets.  Not of 
much use for aquarium keeping.  Other chapters also start from a point 
of view so wide as too me useless, and only narrow down to something useful 
after a few paragraphs or pages.

A third problem relates to the tables used in the text.  One of the good 
things about this book is the large number of tables and charts.  One of 
the bad things about the book is how poorly they are handled.  Some are 
unnessesary, some are hard to interpret, and some are dangerous.  Some 

Table 1, Chapter 4 (page 55) 
The information in this table is not used anywhere else in the book, and 
seems to be useful only to Trivial Pursutes players.
Table 4, Chapter 10 (page 194) 
Notice that this table is for 0 degrees Centegrate, a tempurature that 
few, if any aquarists, care about.  It may be valid at other tempuratures, 
but the text does not enlighten the reader.
Table N, Chapter C (page XX) 
There are three different types of dots, which all look the same, unless 
you have a magnifing glass, but don't worry, I don't think the different 
data points matter.
Table 2, Chapter 19 (page 460).  
I think there is a typo here, but it is hard to tell.  Are microbenthos 
smaller than 0.1 mm in size, or bigger?
Table 7, Chapter 19 (page465). 
This table "Basic feeding process in a single-celled protozoan." is totally 
useless.  The information it contains is not used anywhere else in the book, 
and is not of use to most aquariusts.  (The same could be said of most of 
the figures in this chapter.)

And so on...

As a final, minor point, aquarists who read this book will be confused, at 
first, by the handling of nitrates and nitrites.  The authors refer to 
these as collectively as "nutrients," something I've never heard 
in aquarists circles.

The book has an index, which is not great.  I tested the index by looking up 
"refugium", a part of an algal scrubber.  There was one reference, page 
270.  There is some information of refugia there, but there is far more on 
other pages in the book, which are not in the index.

In summary, the information useful for aquarists in this book could easily be 
put into a single chapter in another book, or a series of magazine articles.  
If you are a hobbiest trying to understand an use scrubbers in your tanks, I 
would start by reading chapters 12 and 21-24 (whichever applies to your 
situation), and then go back and skim or read only those other chapters you 
find interesting.

From: (Joshua Levy)
Newsgroups: rec.aquaria
Subject: My Review of Dynamic Aquaria (part 3)
Date: 27 Oct 1994 17:19:46 -0700
Organization: VERITAS Software Corp., Santa Clara  CA
Lines: 151
Message-ID: <38pg32$>

A Review of Dyamic Aquaria
Part III: A Scrubber Summary

Joshua Levy
(San Francisco Aquarium Society, American Livebearer Association)

The reviewer's background and modivations are described in part I.

What I really wanted from _Dyamic_Aquaria_ (DA) was a scubber cookbook: 
something which would tell me why scrubbers where a good thing, and how 
to build and use them.  As described in this review, parts 1 and 2, I 
did not find that.  Therefore, I have added this part III to my review 
of this book.  This part is a summary of scrubber information for 
freshwater tanks as found in DA.  It is my hope that this will same 
some hobbiests from having to buy the book.. This information in this 
summary is pulled most from chapters 12 and 24 (about 40 pages out of 
600).  A few facts were pulled from other parts of the book.

One of the problems with DA (from a cookbook point of view) is that 
it does not say what is required and what is mearly a good idea.  
Things are described in terms of better and worse, but not suffient 
and insuffient.  For example, centrificle pumps are described as bad, 
because they kill planktons, and most of the scrubber tanks described 
in the book do not use them.  But a few do.  What are we to do?  The 
answer is not clear.

From the point of view of someone doing ecosystem management, this 
makes perfect sense.  They are striving for a perfect simulation.  
But from the point of view of a hobbiest, this is bewildering, since 
there is no way to tell what is enough.

In part 1 of my review, I discuss the evidence that algae scrubbers 
are a good way to filter a tank. I will not repeat that material here.  
From here on, it is assumed that scrubbers are the way to go.

Scrubber Construction Summary:
	1. Lots of light
	2. Screens to culture algae tuffs.
	3. Wave like water motion or screen motion.
	4. No pumps which destroy small organisms.
	5. Little or no metals in construction.

1. Lots of light
Scrubbers need lots of light.  The smaller ones used for 70-130 gallon 
tanks are lit with 2, 4, or 6 HO tubes.  The table at the end of this 
part contains the exact number of eistiens of light each scrubber used.

2. Screens to culture algae tuffs.
DA suggests a 1mm by 1mm mesh, but points out than 2mm by 4mm mesh 
is commonly available for use as window screening, and it is more 

3. Wave like water motion or screen motion.
According to DA waves are very important to algae growth.  All algae 
scrubbers described in the book have them, even the fresh water ones.  
Four different wave generators are described, one using a "dump 
bucket", one using, and two using motors.

4. No pumps which destroy small organisms.
DA advocates pumps which do not destroy small organisms.  Centrifical 
pumps are out.  However, they also describe scrubbers which use them, 
so it is not clear how important this is.  Unforntuantely, according 
to DA there are no pumps which are safe (for small organisms), reliable, 
and cheap.  Aquarists are on their own.  The scrubbers used on the 
aquariums in the book used large diameter diaphram pumps, which started 
life as hand bilge pumps, but were modified and attached to moters.  
The authors also suggest direct suction pumps, or archimeadiean screews.  
None of these are commercially available.

5. Little or no metals in construction.
The DA authors are very worried about metals in the construction 
of aquariums and plumbing.  They point out that zinc is very toxic, and 
commonly used in galvanizing, and "stainless steel" contains iron 
and lots of other stuff that can be toxic.  Metal usage is minimized 
in scrubbers and their tanks.  DA recommneds plastics, and especially

Scrubber Maintence Summary:
	1. Check all moving parts for signs of jamming or breaking.
	2. Remove some algae on a regular schedule.

1. Check all moving parts.
This is self describing.  Moving parts are the ones which fail, so 
they need to be checked regularly.  (Also, it makes sense to design 
wave makers in scrubbers so that if they fail, they do not flood a 
room or empty a tank.)

2. Remove algae.
Harvesting algae is a central part of scrubbers.  It is equivelent 
to cleaning a conventional fitler, and just as important.  (Although 
an algal scrubber will not fail catastrophically if not cleaned, 
they will become less effective.)  If you are feeling really cool, 
you can measure the amount of food you put in (it is 15% nitrogen), 
and compare it to the weight of the algae you harvest (I can't 
remember how much nitrogen it is) so that you have a balence between 
inport and export.  If you are feeling cooler than cool, you can do the 
same for other trace nutrients, like phosphorous.

Technically, that is all you need to worry about for the scrubbers.  
They are not that difficult.  They do not, however, exist in a 
vacume, they exist connected to a tank.  DA has a lot to say about this 
tank, so I've included some of that material below.  Remember that 
DA is about ecosystem simulation, not traditional aquarium keeping, so 
some of the comments below will not apply.

Tank Summary:
	0. Learn about the ecosystem you are reproducing, and reproce it.
	1. Lots of light
	2. A "real" bottom.

0. Learn about the ecosystem you are reproducing, and reproce it.
This is the first commandment of the microcosm builder.  You should 
have the same substrate as the ecosystem you are modeling, the same 
animals, plants, water, light, etc.  There is no such thing as too 
much research.

1. Lots of light
Not only more light, but better timed light.  DA points out that 
there is more light in nature than is found even in the brightest 
reef tanks.  Also, that the length of a day changes throughout the 
year, and this fact should be modeled.  Finally, the authors do not 
like "gro-lux" type lights, because they are optimized for 
very specific plants.  The authors believe that a whole ecosystem 
should be lit with the whole spectrum.  If the plants only use parts, 
other things will use the rest.

2. A "real" bottom.
DA strongly recommends a real bottom, the same substrate as is 
found in nature.  In particular, dirt/mud bottoms are far more 
common in nature than in aquariums.

Summary of scrubbed tanks:

This table is taken from page 238 of DA.  I have only included 
"aquarium type" tanks (under 1000 gallons).  Note: this table is
best printed on 132 column paper.

Name	Tank					Scrubber				Waste	Pumping
	Surface	Volume	Lighting		Power	Surface	Lighting		Power	
Reef	0.85	130	VHO/6/960	1129	0.18	HO/6/300	1670	0.5-1.0
ChPk	0.85	120	VHO/6/960	816	.082	HO/4/140	1700	---
African	0.51	70	VHO/2/230	450	.085	HO/2/70		823	8-16
So.Am.	0.51	70	VHO/2/230	450	.072	HO/2/70		970	<1
Surface is surface area in square meters.
Volume is in gallons.
Lighting is the type, the number of tubes, and total wattage.
Power is watts per square meter.
Waste, is nitrites and nitrates, in micro Moles (70 = 1 ppm approaximately).
ChPk is a Chesapeake home aquarium.
African is a African pond aquarium.
So.Am. is an Black water (South American) aquarium.

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