Low Energy System Design

...Download this Sketchup Model..

This system has two radial filters and a media bed to keep the deep water culture raft very clean, An airlift pump keeps the water moving via an air compressor; no mechanical water pumps are required

Water levels in all the tanks are the same. By not raising the water from a sump tank only a small amount of energy is required to move the water laterally.

If this entire system were buried flush with the ground the thermal mass of the earth would help regulate the temperature very well during both summer and winter 

Airlifts  provides both water circulation and aeration. I believe airlift pumps can be more efficient than an external pump.  (I've never understood why submersibles are always less efficient, but the specs tend to indicate this).
Airlifts can be calculated.
This article Performance Study of an Airlift Pump with Bent Riser Tube presents an interesting conclusion is that bends in the riser pipe do not effect the performace of an airlift pump.
OPTIMIZATION OF A BACKYARD AQUAPONIC FOOD PRODUCTION SYSTEM
is a very good paper about aquaponics and it would be a very good source for information about airlift pumps but a critical table is missing.  I'd still recommend reading it for everything else it presents.



I found this calculator for airlift pumps.  It is spot on against the real life experiments I've conducted.

From my own experiments without math; I believe an airlift will provide enough water circulation.  That is also what Keith Tatjana demonstrates in his paper in which he assumes a circulation rate of one fish tank volume twice per hour.
I think air blowers are more reliable than water pumps, and less expensive.  Blowers do not provide the pressure like a compressor so this is a limiting factor when using a blower, but if at all possible use an air blower because air compressors like the Hydrofarm 70 and 110 lpm units tend to vibrate themselves to death.
I have not done any experimentation with how much ambient air temperature will affect the water temperature, but logically this would occur whether it be from an air stone or an airlift pump.
Other papers I've found are

Performance Characteristics of Airlift Pumps withVortex Induced by Tangential Fluid Injection

Explore the Potential of Air-Lift Pumps and Multiphase   Explore the potential of air-lift pumps  A geyser pump, an improved airlift pump The Geyser Pump improved the amount of water pumped from 40 gpm to 60 gpm in one experiment I conducted.   This Video shows the Geyser Pump I built. http://youtu.be/ztHBHULkHNQ

Drums

Nice Clean Design

I like the way these drums are supported.  In the past I've always seen drums supported from below.  This looks strong to me and the clutter of support beams has been eliminated.  

This span proved to be a bit too long.  Support will be added in the middle

I'm not advocating the use of non-food grade drums, but recently I was given quite a few.   I did some looking into the hazards of the contents which were products used at a car wash.  One of the barrels was very clear about not reusing the drum and so I will not reuse it.  But I still question the reason for the warning.

If you want barrels look for free drums at food processors and restaurants.  Here is Chico we are lucky to have Smukers / R.W. Knudsen where we can buy various food grade containers for only $5.00

Here is what I found

The Rain X and Blue Coral drums contain Butoxyethanol which causes damage to the following organs: blood, kidneys, liver, lymphatic system, upper respiratory tract, skin, central nervous system, eye lens or cornea.
Butoxyethanol appears to be toxic in high doses of 100-500ppm, but 2-Butoxyethanol usually decomposes in the presence of air within a few days, and has not been identified as a major environmental contaminant. It is not known to bioaccumulate
These products are not required to list it on the label when diluted to a certain point. The safety of the products as normally used is defended by the American Chemistry Council and the Soap and Detergent Association, industry trade groups.


Blue Coral Lo pH Conditioner Yellow
"Empty containers retain product residue and can be hazardous. Do not,reuse container. "
This warning says it all, but from the list of ingredients it seems that only the sulfuric acid gives reason for such a strong warning.
Contains:
Sulfuric Acid - highly corrosive strong mineral acid
Cocamidopropyl betaine - A synthetic surfactant used as Antistatic Agent; Hair Conditioning Agent; Skin-Conditioning Agent
Benzenecarboxaldehyde, - artificial almond oil.  It is not considered an air or water pollutant nor is it considered toxic.  None of the chemicals in this product are considered highly hazardous by OSHA.


DEF - Diesel Exhaust Fluid
Contains:
Urea - Diesel Exhaust Fluid is clear non-hazardous liquid. 
Appears to me to be relatively safe when diluted.

Super Suds 6062
Contains:
Potassium Hydroxide commonly called caustic potash is used in hand soap and appears to me to be relatively safe when diluted.
Sodium Metasilicate is used in wine and beer and appears to me to be relatively safe when diluted.
Sodium Phosphate, Tribasic  - TSP is a common household cleaning product and appears to me to be relatively safe when diluted and rinsed clean.

Blue Corral Velocity Clear Coat Protestant
Contains:
Butoxyethanol - See description above

Blue Coral Clear Coat Polish
Contains:
Butoxyethanol - See description above
Propan 2 ol  is Isopropyl alcohol aka 'rubbing alcohol'.


Rain-X Online Protectant
Contains:
Butoxyethanol - See description above
Propylene glycol (PG or MPG)   - A colorless, odorless liquid which is generally recognized as safe (GRAS) by the U.S. Food and Drug Administration (FDA) in 21 CFR § 184.1666, for use as a direct food additive under the conditions prescribed. It is approved by the U.S.
Acetic Acid is an acid which is caustic in high dilution but in diluted forms such as vinegar it would seem relatively safe.