Aquaponics Digest - Fri 12/03/99
Message 1: Re: Fw: Greenwater Culture in Israel.
from "James Rakocy"
Message 2: Fwd. request - Kosher TILAPIA WANTED
from S & S Aqua Farm
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| Message 1 |
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Subject: Re: Fw: Greenwater Culture in Israel.
From: "James Rakocy"
Date: Fri, 3 Dec 1999 12:30:41 -0400
Sam, We are working on greenwater technology here in the Virgin Islands. We
plan to build two circular greenwater tanks early next year. They will be
200 m2. In our experiments so far we have been able to produce 17 kg/m3
using Nile tilapia. Our water exchange rate is much lower, less than 1%.
We only remove water containing sludge, which is a nice dark green color,
indicating the removal of dead algal cells. I would be interested to learn
about construction techniques. We plan to build one tank with a standard
block wall and the tank will be lined with 30 mil high density polyethylene.
We will slope the bottom to a center drain by 1 to 2% and insert a 1 m3 cone
(45 degree slope made of thicker lining material) in the center of the tank.
The other method will use a speed block wall and a concrete bottom. I
understand that speed blocks involves a combination of poured concrete core
and a block outer wall, almost like a permanent form. I want to compare the
cost, ease of construction and durability of these methods. I'm not too
familiar with concrete work. I would like to know the best way to pour a
200 m2 concrete floor. How thick should it be? What type of reinforcing is
best? There will be a 18 inch wide by 1 foot deep footing around the
perimeter. How does one assure a good seal between the wall and the footing
and the floor and the footing? Also, how does one make a 45 degree cone out
of concrete? Does it require a form or can you use a drier mix and shape it
without a form. I understand that many Israeli greenwater systems are out
of use? Is this true and why? Anyone good with concrete? Jim R.
----- Original Message -----
From: Sam Levy
To:
Sent: Friday, December 03, 1999 1:39 AM
Subject: Re: Fw: Greenwater Culture in Israel.
> ted--
>
> hope you get this before you're off list.
>
> greenwater is typically done here in earthen ponds or in lined ponds using
> water from earthen ponds.
>
> what i will describe here is a system that's a little different but deals
> with some of the issues you raise.
>
> this strategy is practiced in plastic lined (or concrete) ponds and is
> designed to maximize the utilization of nutrients.
>
> the aerators (paddlewheel / fountain) are placed to maximize the continued
> presence of particulate matter in the water column. the tilapia are fed a
> commercial diet of 25 - 35% protein (depending upon availability) and 3 -
5%
> lipid. water exchange is 5 - 15% daily (sometimes as low as 3%). the
ponds
> are typically flushed twice/day to eliminate settled solids. the fish are
> stocked for growout at around 100 grams. planned maximum density for a
pond
> will be 16 - 20 kg/sq m. this strategy is practiced in ponds of 100 - 250
> sq m (possibly up to 400 sq m). small juveniles will be reared to around
5
> - 7 kg/m @ 5 grams. advanced juveniles to 10-15 kg/m.
>
> the essential process is the the conversion of carbon and nitrogen into
> bacterial protein (floc) which the fish ingest. again, this is a strategy
> for maximizing feed utilization and may result in slower growth and lower
> densities compared to other management systems.
>
> it is also a system that requires careful monitoring for oxygen and
> nitrogenous wastes--as you can well imagine. the water will often be a
> lovely brown color.
>
> tilapia do well and carp may be added to help keep the bottom stirred
up--it
> remains to be tested with other species.
>
> looking forward to your return,
>
> sam
>
> >From: "TGTX"
> >Subject: Fw: Greenwater Culture in Israel.
>
> >
> > > I would very much like to hear from any Israeli Tilapia farmers on the
> > > fundamentals of greenwater Tilapia culture as it is practiced in
Israel.
> > >
> > > 1) How protein content (%) in feed pellets may be lowered in
greenwater
> > > culture, and in what manner (in stages or degrees, or at all growth
> >stages)
> > > to take advantage of the algae & suspended bacteria food source and
the
> > > algae-heterotrophic bacteria function of assimilating nitrogenous
waste
> >into
> > > their biomass.
> > >
> >
> > > 4) I dimly recall some carbon isotope studies of greenwater Tilapia
> >culture
> > > conducted (I believe) in Israel, indicating that approximately half of
> >the
> > > assimilated carbon that went into the fish came from the artificial
> >pellet,
> > > whereas the other half orginated from photosynthate carbon and
possibly
> > > recycled ambient carbon sources from heterotrophic bacterial
> >biomass...can
>
> > > Sincerely,
> > >
> > > Ted Ground
> >
> >
>
> ______________________________________________________
> Get Your Private, Free Email at http://www.hotmail.com
>
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| Message 2 |
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Subject: Fwd. request - Kosher TILAPIA WANTED
From: S & S Aqua Farm
Date: Fri, 03 Dec 1999 13:51:31 -0600
I've received an inquiry from:
"the largest kosher supermarket south of New York, and we would
like to bring tilapia to sell both here in Miami and in New York."
If anyone's interested in following up with this individual to supply:
"kashrut certified or receive the fish skinned with a small portion of skin
showing (at the tail?)."
Let me know at , and I'll forward the contact info
to you.
Paula
S&S Aqua Farm, 8386 County Road 8820, West Plains, MO 65775 417-256-5124
Web page http://www.townsqr.com/snsaqua/
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