Aquaponics Digest - Thu 03/09/00 




Message   1: Re: Experimental lighting questions
             from "Sam Levy" 

Message   2: Any suggestions
             from Attie Esterhuysen 

Message   3: Re: Any suggestions
             from "James Rakocy" 

Message   4: Re: Any suggestions
             from MUDDTOO

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| Message 1                                                           |
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Subject: Re: Experimental lighting questions
From:    "Sam Levy" 
Date:    Wed, 08 Mar 2000 23:17:10 PST

>>
>Good one, Sam, I was going to suggest the very same thing.

thanks, ted--
sam
>

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| Message 2                                                           |
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Subject: Any suggestions
From:    Attie Esterhuysen 
Date:    Thu, 09 Mar 2000 08:18:49 GMT

Hi everyone

I need your suggestions on the following. In my previous 
post I asked questions about the climate etc. Thank you very 
much for your replies. Today I want you to comment on my 
proposed system as well as on the water analysis. The system 
layout will look as follows.
Water reservoir, Trout tank, mini wetland, hydroponic 
system, slow gravel filter, sump.

The idea is to drain the water from the fish tank's center 
point. The inlet water will come in near the wall in a 
direction parallel to the wall. I am hoping to create a 
large enough vortex to effectively remove all the solid 
waste. At the inlet some sort of  an aerator is needed. 
Please advise on which aerator you find the most efficient.

>From the fish tank the water will first flow through a mini 
wetland system. The only reason for this is to remove all 
the solid waste from the water before it enters the 
hydroponic system. Since there is growing an indigenous 
meadow, wetland, grass on the farm, I was thinking of using 
it for this purpose. The area will depend on the amount of 
solid waste.

Next the water will flow through the hydroponic system, 
hopefully cleaned of solids. 

Since I read in an article about a slow gravel filter's 
ability to remove bad bacteria from the water, I was 
thinking of using it after the hydroponic system. The idea 
is to perhaps also plant bulrushes and Yellow flag in the 
filter media. The reason for the plants are to remove 
unwanted NaCl and to help sterilize the water. Here I refer 
to an internet article at, 
http://www.ratical.org/LifeWeb/Articles/rushes.html . Please 
comment on this article.

>From here the water will flow into a sump from where it will 
be pumped to the reservoir.

The wetland plants will be cut on regular intervals to be 
used as sheep fodder or as compost roughage. 

The water that is going to be used will be either borehole 
water or rain water. The borehole water's analysis is as 
follows.

PH = 7.3, EC = 1.29

m mol/l
K = 0.1
Ca = 1.9
Mg = 0.1
Na = 5.5
NH4 = 0.02

Micro mol/l

B = 33
Zn = 0.5
Cu = 0.4
Fe = 1.3
Mn =0.8

mmol/l

NO3 = 0.1
P = 0.01
SO4 = 2.7
HCO3 = 5.0
Cl = 3.5

Could you also advise on fish density and water flow rate 
for close looped systems.

I am looking forward to your suggestions.

Have a wonderful day.

Attie

 

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| Message 3                                                           |
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Subject: Re: Any suggestions
From:    "James Rakocy" 
Date:    Thu, 9 Mar 2000 14:49:25 -0400

> Could you also advise on fish density and water flow rate
> for close looped systems.

You should shoot for a final rearing tank density of 0.5 lbs/gallon (60
kg/m3) and an water exchange rate in the rearing tank that can vary from
roughly 60 minutes or greater at stocking to nearly 30 minutes at harvest.
Jim R.

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| Message 4                                                           |
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Subject: Re: Any suggestions
From:    MUDDTOO
Date:    Thu, 9 Mar 2000 23:42:19 EST

In a message dated 3/9/00 10:48:43 AM Pacific Standard Time, jrakocy@uvi.edu 
writes:

> 
>  > Could you also advise on fish density and water flow rate
>  > for close looped systems.
>  
>  You should shoot for a final rearing tank density of 0.5 lbs/gallon (60
>  kg/m3) and an water exchange rate in the rearing tank that can vary from
>  roughly 60 minutes or greater at stocking to nearly 30 minutes at harvest.

Hi all,

Any idea on the amount of nutrient that could be available at max fish 
capacity and with an exchange rate of 30 to 60 minutes?

Do you expect to have fairly clean water, clean of all nutrients, from the 
return line at these rates?

Thanks, Joel
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