Backyard Aquaponics
A place to discuss aquaponics

Doug,
this thread is about energy efficiency
while air pumps and diffusers undisputably have a historically established place both in aquaculture as in aquaponics, only measurements or/and calculation can determine whether or not they are energy efficient either at pumping or at aeration
1. pumping: So far ALL examples of airlift pumps I have found that mentioned head, volume and power consumption have failed the test and shown extremely energy inefficient. I have found not one single exception. I am quite ready to change my opinion if only someone would bring up an example of an energy efficient airlift pump
2. aeration: ALL papers I have found on efficient aeration with bubbles speak of submergence rates FAR higher than existing in aquaponics or aquaculture. deep submergence equals high energy demands. Furthermore efficiency of bubble aeration is dependent on the size of the bubbles: only very tiny bubbles achieve an acceptable aeration rate because of two factors: they expose more surface and they float more slowly upwards (hence the need for deep submergence).
diffusers capable of producing extremely small bubbles at great depth are high tech and very expensive. and by their nature they are prone to clogging and need a lot of maintenance.
none of these conditions are met in either aquaculture or in aquaponics
these are facts or at least I have found not one single evidence against it (and I have done a lot of searches and still continue doing them)
next follows an opinion, not a fact:
I presume that pumps are much more efficient at both tasks because for the same energy input they move much more water (not bubbles), thus have the potentiality of exposing more water surface to air surface on one condition: in a well designed system where all possibilities of passive aeration are exploited.
open gutters, flow forms, cascades, turbulent flow versus laminar flow, counter current ventilation, etc...
I know I am sticking my neck out by stating this as it is against general belief
a lot of the first people that dared to suggest that the earth is round were beheaded or crucified.
no doubt there will always be a place for airlift pumps and diffusers
just like there will always be a place for pen and paper while we all know that computers are much more efficient
the only advantage air driven systems have is that they SEEM easily applicable
but don't let yourself be fooled by impressions: adjusting an airlift pump for best performance is very complicated.
the diffusion of bubbles over a 1 m wide circle shows exactly that: the diffusion of bubbles, not of any substantial amount of water
just like to the eye you might think that a lot of water is moved but how can you tell? your eyes cannot ignore the bubbles that fool your impression
please contradict me
it is my honest opinion that airlift pumps and diffusers have no place in a system that pretends to try to be energy efficient.
greetings
frank

Diffused Air
This type of aeration in large shallow aquaculture ponds is almost completely ineffective as it generally only performs functions 1 and 2 in a limited capacity. This form of aeration regularly comes in as the least cost efficient form of aeration. The efficiency of this type of aeration is also greatly dependent upon the size of the bubble (the finer the bubble the greater the efficiency but fine diffusers foul or block more rapidly) and the way in which they are installed (loose or in airlifts). Purpose-built aquaculture ponds are generally shallow (1-2m) and since this type of aeration is also dependent upon the contact time between the water and the bubble the Department of Fisheries is usually just not enough to allow long contact times, although U-tube airlifts can be used to improve contact duration. It is however a good system in deeper water (>5m) such as water supply dams. The use of a number of air diffusers scattered around a pond is probably the most inefficient system and the aeration effect is usually very localised around the diffuser (Fig 1a). Air lifts can be used to improve mixing and help generate currents (Fig 1b). Boyd (1995) described a shallow pond compressed air aeration system that performed well but would probably not be suitable for crayfish production. Generally diffused-air is the most inefficient way to aerate a pond when the hp required or dollar cost per unit of oxygen is calculated (refer to Table 1).

Dogma (the plural is either dogmata or dogmas, Greek δόγμα, plural δόγματα) is the established belief or doctrine held by a religion, ideology or any kind of organization, thought to be authoritative and not to be disputed, doubted or diverged from.

Even Frank has to run low densities because he relies on other methods of getting the o2 into the water.

I don't see the need for a balancing act where the flip side is stressed or dead fish

but for the most of us it is a question of why bother.

More air = happy fish.

on the stand of my main supplier (and personal friend) there were people from the factory (Speck Pumps)
They build a.o. huge propeller pumps
I had a long talk with them and have caught their attention

But if you do a search on anything related to airlift and air pumps there you are guns a firing. Why is that?

on the stand of my main supplier (and personal friend) there were people from the factory (Speck Pumps)
They build a.o. huge propeller pumps
I had a long talk with them and have caught their attention

did you want to ask a question about this?

frank

are you in any way insinuating that I am sponsored, Dufflight ???

????????????

if so:
please stand up for it and say it to my face

insinuations are just about the lowest way one can one get to try and win a debate !!!

frank