Grow bed media - depth discussions

veggie boy

From the DPI Victoria site:

Stocking Densities

The loading capacity of recirculating production systems depends on flow rate, oxygen availability, filter and heat exchange unit efficiency and the particular requirements of the culture species. These requirements vary between species. For example, under optimum conditions eels can be grown at stocking densities of >300 kg/m³ whereas Murray cod can be grown at >100 kg/m³. The higher the density that a species can be cultured without negatively impacting growth rates or fish health, the more viable recirculating systems are. Another important factor in the viability of recirculation systems is the market price per unit product.

Here they are talking about Murray Cod at greater than 10kg per 100 litres (say at least 2 times what we would see as max in AP) and eels at 30kg per 100 litres (5 times out max).

steve

veggie boy

Go the eels.

steve

imagine falling into THAT IBC :shock:

sounds like the making of a B grade horror movie

Stuart Chignell

Ok VB your point has carried. Thank you for following through on it. That 1kg/10L for the murray cod that had to be with added O2 yes?

From previous posts I thnk the general concensus was that even if ew could grow at those densities we wouldn't? Battery hens and all that.

MMM smoked eel

Stuart

raimiuso

earthbound wrote:

There are so many thing not understood about the complex relationships in aquaponics, things that don' seem right either.... I asked Dr Rackocy about the UVI system last year when he was in Melbourne, "don't you find that you have a lack of nutrients in your water once the water has travelled through 60m of plant roots and it's getting to the last plants before it goes back into the fish tank? Surely these plants at the end would suffer?" His answer was that the nutrient levels are the same at the end as they are at the start.... How the hell does that work..?

In discussions with Nick Savidov earlier this year, he believes it is simply just huge flow rates that allow this to occur. They pump 400L/min. :shock:

(They run the exact same system as Dr. Rackocy)
From a Production Evaluation Booklet on their system:
"Water circulated through the system at 400L/min. Each fish tank received a flow of 100L/min and each plant tray a flow of 200L/min."

earthbound

200L a minute isn't really a great flow through the plant trays, when you look at the cross sectional dimensions of the floating raft beds.. Flows can't be too strong or the roots can suffer..

If you consider that their raft beds are 1200 x 300 (they may be deeper), this means that a flow of 200L a minute equate to about 50cm a minute, or 30M an hour.. If I've done my calcs correctly..

Backyard Aquaponics A place to discuss aquaponics

Grow bed media - depth discussions

Backyard Aquaponics
A place to discuss aquaponics