NANFA-- Fw: AES Splash 6-07-01

B.G. Granier (
Fri, 8 Jun 2001 17:55:11 -0500


----- Original Message -----
From: Aquatic Eco-Systems <>
To: <>
Sent: Thursday, June 07, 2001 11:42 AM
Subject: AES Splash 6-07-01

A Publication for Aquatic Eco-Systems Customers
Volume I, Issue 9

Welcome to the ninth edition of Splash. We hope to keep this
newsletter both informative and entertaining, so your comments and
suggestions are always welcome. We also accept contributions - please send
them to us at .

Tech Talk

Aeration and Energy

Aeration can be accomplished by mechanical
aerators or underwater air diffusers. Mechanical aerators agitate water to
produce liquid/air contact, while underwater diffusers introduce bubbles
from a depth to achieve oxygen transfer and mixing. Bubble type aeration
systems are replacing many mechanical aerators because of their low
maintenance, reliability, safety, flexibility and overall efficiency. They
excel where small amounts of aeration are needed in many locations. Bubble
aerators are also better at removing gases, such as ammonia and carbon
dioxide. Diffusers are made to deliver either coarse (approximately 6 mm),
medium (approximately 3 mm), or fine (approximately 1 mm) air bubbles.

Coarse-bubble systems require the lowest air pressure and are very resistant
to clogging, but are about a third as efficient as medium-bubble systems in
transferring oxygen to the water. The medium-bubble diffuser requires only
slightly higher air pressure, but its superior oxygen transfer more than
compensates for the
increase in maintenance due to occasional clogging. The fine-bubble
diffuser's superior oxygen transfer usually does not compensate for its
higher-pressure requirement and much more frequent clogging. Therefore,
fine-bubble diffusers are typically chosen for pure oxygen or ozone systems
where pressure requirements are less important than transfer efficiency.
Overall, however, medium-bubble diffusers are the most popular among

Diffuser clogging often occurs from the inside. It is caused by dust and
dirt particles carried by the air supply or by impurities in the water.
Calcium carbonate often forms a deposit that clogs the pore outlet. (This
source of plugging is prevalent in hard water and salt water.) Another
source of plugging is bacterial slime, which forms on the external surface
of the diffuser. Replacing medium and fine-bubble diffusers with
coarse-bubble diffusers might seem like a good way to avoid periodic
cleaning, but it's not very cost-effective. Let's work out the economics on
a 10 horsepower system:
If a 10-horsepower medium-bubble aeration system can support
40,000 pounds of fish, a coarse-bubble system would require 30
horsepower under the same conditions. Electricity currently costs about $60
per horsepower per month in our area. This would make the utility cost rise
from $600 a month to $1,800 - that's an extra $14,400 per year paid to the
power company. An additional 20 horsepower in blowers would need to be
purchased, as well as a larger diameter air-distribution pipe, if
coarse-bubble diffusers were chosen over medium bubble diffusers.

Diffuser placement should allow for easy removal and time
should be allotted to clean all the diffusers in one section at one
time. This not only reduces the aggravation created by multiple
individual cleanings, but it also suggests when to schedule the next
cleaning. With our SweetwaterŽ glass bonded diffusers, frequency of
cleaning can range between once per month in very hard water to once per
year in soft water. Aquatic Eco-Systems, Inc. introduced the low-pressure,
low-maintenance, medium-bubble air diffuser to the aquaculture industry in
1978. Our glass-bonded silica diffuser is still the standard. We're always
looking for a better diffuser; that is, one with finer bubbles, lower
pressure loss, self-weighting, non-clogging and less expensive. When we
find one, we'll let you know. If you find one, please let us know.


On The Lite Side

A new computer that was practically running all the business
in one office suddenly stopped working. No one in the office could
locate the trouble, let alone correct it, so they called in a consultant.

When he arrived, he opened his briefcase, took out a small
hammer, and tapped the side of the computer. It started working
immediately. The consultant packed his hammer and prepared a bill for $500.

The office manager was outraged. "All you did was tap on it
with a hammer," he said. "I want an itemized bill!"

The consultant took back the bill and wrote on the bottom: "Tapping
computer - $1. Knowing where to tap - $499."


Don't forget to visit our Classified Ad section to check the wide variety of
notices our readers send us. See our listing of ads at and send in one of your



Free Palm Aquarium!

We're giving away the "Blessing II" palm aquarium.
Coupon code: 54322
Click here to see the details!


<<<>>> <<<>>> <<<>>> <<<>>> <<<>>> <<<>>> <<<>>> <<<>>> <<<>>> <<<>>>
* To remove yourself from this mailing list, point your browser to:
* Enter your email address ( in the field
provided and click "Unsubscribe". The mailing list ID is "aes".


* Reply to this message with the word "remove" in the subject line.

This message was sent to address
<<<>>> <<<>>> <<<>>> <<<>>> <<<>>> <<<>>> <<<>>> <<<>>> <<<>>> <<<>>>

/"Unless stated otherwise, comments made on this list do not necessarily
/ reflect the beliefs or goals of the North American Native Fishes
/ Association"
/ This is the discussion list of the North American Native Fishes Association
/ To subscribe, unsubscribe, or get help, send the word
/ subscribe, unsubscribe, or help in the body (not subject) of an email to
/ For a digest version, send the command to
/ instead.
/ For more information about NANFA, visit our web page,