Aquaponics Digest - Fri 03/24/00
Message 1: Belt feeders, etc.
from "Steve"
Message 2: Re: more duckweed
from "Steve"
Message 3: Re: Any suggestions
from Chris Weaver
Message 4: Re: Belt feeders, etc.
from "beacnhrt"
Message 5:
from Joe_Myers@mail.mda.state.mo.us
Message 6: Re: more duckweed
from tvoivozhd
Message 7: Re: Any suggestions
from "Barry Thomas"
Message 8: Re: Belt feeders, etc.
from PHILIP N BURNETT
Message 9: Cooling bolting lettuce
from Tony Cooper
Message 10: Duckweed feeds
from Tony Cooper
Message 11: Oxygen Cone
from "Jay Myers"
Message 12: Re: Oxygen Cone
from "fkious"
Message 13: Re: Any suggestions
from "Sam Levy"
Message 14: Re: Belt feeders, etc.
from "Sam Levy"
Message 15: Re: Any suggestions
from "Sam Levy"
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| Message 1 |
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Subject: Belt feeders, etc.
From: "Steve"
Date: Fri, 24 Mar 2000 01:02:32 -0600
Hi guys & girls,
Got another question to throw out.
I, as do most of you, work a "real job" & sometimes put in long
hours.....sometimes 12-hour shifts and sometimes 16-hr shifts. If you assume
1 1/2 hour round-trip drive times and getting ready to go to work, etc. etc.
sometimes, it is 12, 14 or even 18 hours between feedings of my Tilapia.
This includes feeding of the babies (which are suppose to be fed
6X/day....LOL.)
This greatly reduces the growth of the fish (obviously). When I get home and
feed them, they are just starving.
Anyone have any experience with belt-feeders (or other means of feeding) and
a good (reasonably priced) place to shop for them?
I am also trying to find a good source for watercress to place in the tanks
so they can "graze" as well as feed. I have a source to call tomorrow. If
this goes well & anyone is interested, I will gladly pass on any information
I receive.
Thanks as usual.........Steve
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Subject: Re: more duckweed
From: "Steve"
Date: Fri, 24 Mar 2000 01:16:59 -0600
Hi,
Sorry, didn't get your name...for some reason, the email cut off.
If you are under a deluge of watercress as you say, would you do an aspiring
aquaponics person a favor and overnight a pound or so to me. (I choose
overnight because I understand that they don't ship well.)
I would, of course, pay for any expense.
Thanks a lot.........Steve
----- Original Message -----
From: "tvoivozhd"
To:
Sent: Tuesday, March 21, 2000 7:58 AM
Subject: Re: more duckweed
>
>
> Tony Cooper wrote:
>
> > Glad to see the duckweed thread going as i am doing a growing trial
> > with it right now.
> > I collected some along the edges of a nearby stream and divided it into
> > two 3 ft square trays, one with water from the tilapia tank and one with
> > a weak hydroponic solution EC 0.7, both filled 2 inches deep and placed
> > in a sunny area.
>
> Tvoivozhd---I monitor this group, but don't dip in often because I am
> already flooded with e-mails, and more interested in duckweed as a
polisher
> for sewage treatment.
>
> However, does anyone possess statistics on the growth of watercress? I
have
> a pond forty feet above my gardens that I use for gravity irrigation. The
> pond contains a lot of duckweed, but the more rapidly moving stream in and
> out of the pond is full of watercress---storm torns strands of which have
> created islands of watercress for miles downstream.
>
> I'm pretty sure watercress would appeal to tilapia, its growth
accellerated
> by the nutrients y'all are trying to get rid of, and if your market is the
> chefs of upper crust hotels and restaurants, watercress should have a
ready
> market for garnishes, soups and salads.
>
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| Message 3 |
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Subject: Re: Any suggestions
From: Chris Weaver
Date: Fri, 24 Mar 2000 07:59:18 -0500
Try looking up the web site for Aquasafra. They have a chart that shows
weekly growth rates from 1 gram to 683 grams (1.5 lbs).
www.tilapiaseed.com
Barry Thomas wrote:
>
>
> Do you (or anyone) know of any (online) growth curves for tilapia (and
> trout)?
>
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Subject: Re: Belt feeders, etc.
From: "beacnhrt"
Date: Fri, 24 Mar 2000 09:04:28 -0600
Dear Steve,
Automatic feeders was our main business for a long time. Contact me off
the list and I will let you know what we can do for you.
melvin landers
beaconhort@thecenter.zzn.com
-----Original Message-----
From: Steve
To: aquaponics@townsqr.com
Cc: Bill
Date: Friday, March 24, 2000 12:50 AM
Subject: Belt feeders, etc.
>Hi guys & girls,
>
>Got another question to throw out.
>
>I, as do most of you, work a "real job" & sometimes put in long
>hours.....sometimes 12-hour shifts and sometimes 16-hr shifts. If you
assume
>1 1/2 hour round-trip drive times and getting ready to go to work, etc.
etc.
>sometimes, it is 12, 14 or even 18 hours between feedings of my Tilapia.
>This includes feeding of the babies (which are suppose to be fed
>6X/day....LOL.)
>
>This greatly reduces the growth of the fish (obviously). When I get home
and
>feed them, they are just starving.
>
>Anyone have any experience with belt-feeders (or other means of feeding)
and
>a good (reasonably priced) place to shop for them?
>
>I am also trying to find a good source for watercress to place in the tanks
>so they can "graze" as well as feed. I have a source to call tomorrow. If
>this goes well & anyone is interested, I will gladly pass on any
information
>I receive.
>
>Thanks as usual.........Steve
>
>
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| Message 5 |
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Subject:
From: Joe_Myers@mail.mda.state.mo.us
Date: Fri, 24 Mar 2000 09:05:36 -0600
unsubscribe
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| Message 6 |
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Subject: Re: more duckweed
From: tvoivozhd
Date: Fri, 24 Mar 2000 11:18:59 -0500
Tvoivozhd, sure, what is your mailing address?
Steve wrote:
> Hi,
>
> Sorry, didn't get your name...for some reason, the email cut off.
>
> If you are under a deluge of watercress as you say, would you do an aspiring
> aquaponics person a favor and overnight a pound or so to me. (I choose
> overnight because I understand that they don't ship well.)
>
> I would, of course, pay for any expense.
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| Message 7 |
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Subject: Re: Any suggestions
From: "Barry Thomas"
Date: Fri, 24 Mar 2000 16:55:26 -0000
Chris,
> Try looking up the web site for Aquasafra. They have a chart that
shows
> weekly growth rates from 1 gram to 683 grams (1.5 lbs).
>
> www.tilapiaseed.com
That's perfect, thanks.
I assume that this is fairly representative (they mention a density of
80kg/M3 which seems higher than most)?
I was quite surprised when I graphed the average weight and growth per
day over time. Until week 10 in their table (14 to 16 weeks from
hatching), growth is slow. Something fairly drastic seems to happen over
the next 2 weeks then slow steady(ish) increase in rate of change of
growth which starts to flatten out after about week 24.
So,
1) This seems to indicate that fixed tanks are somewhat less efficient
than if growth were perfectly linear.
2) What happens at week 10?
I've been trying (in amongst other things) to work out just what kind of
a difference moveable dividers might (theoretically) achieve. Progress
has been slow. I've some ideas to try out over the weekend but I find it
difficult to believe that this hasn't been looked at before. I'd be
grateful to hear of any relevant info, thoughts, news that someone's
already worked it out and posted the results etc.
Thanks again,
Barry
barrythomas@btinternet.com
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Subject: Re: Belt feeders, etc.
From: PHILIP N BURNETT
Date: Fri, 24 Mar 2000 12:36:38 -0800
Rather then a belt feeder would you consider an alternate device.
Deer hunters have a device they put out into the field, this device can
be hung from a tree or on a tripod. This is a battery powered feeder that
can be programmed to shake out feed that will attract deer to a specific
spot. This deer feeder could be use to feed your fish automatically as
many times a day as you like (limited to capacity and program
restrictions of the feeder.
Justa thought
Have fun
Phil
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| Message 9 |
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Subject: Cooling bolting lettuce
From: Tony Cooper
Date: Sat, 25 Mar 2000 09:52:47 -0800
Thanks people for the input on high temperature lettuce growing.
William, Ill see what's available here in semi head types, thanks.
Depressing to see learn that a rotten core is often the result of an
otherwise successful production of hi-temp lettuce.
A friend is building me a solar powered adsorption unit using ammonia.
This is a well known technology but what we are trying for is continuous
operation using a rather novel approach, its a bit hush hush now but
will report if it works.
John, You've knocked my musing about a chest freezer cooler squarely on
the head, but saved me wasting a lot of money. Swamp coolers wouldn't
work too well here with the very high humidity.
As i mentioned, i want to cool the water after it leaves the fish tank,
so that it will be warmed up removing heat from my gravel beds thereby
not lowering the temperature of the tank on its return.
Robert, i think a buried cooling pipe would not work too well here as
the underground temperature is only marginally lower than up top. As the
year round temp is on average pretty constant the sub ground temp wont
go below that average, its fine if you have a cold winter to offset a
warm summer. Incidentally i live very near to Mt. Pinatubo which is
still very hot just below the surface.
There has to be a simple way though if i can only find it.
Tony Cooper
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| Message 10 |
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Subject: Duckweed feeds
From: Tony Cooper
Date: Sat, 25 Mar 2000 09:52:55 -0800
Thanks Ted for all the interesting factoids on feeds ;)
I've sun dried a sample which then has a woolly texture but flakes
nicely when rubbed in the hands and floats without hydrating too
quickly. the fish seem to enjoy it. I shall have to find out about
getting a protein analysis of my local variety when dried.
The preferred live aquatic tilapia feed at the University of the
Philippines at Los Banos is Azolla, they have been working for some
years developing efficient strains but i have found Azolla a little more
sensitive to grow than Duckweed although the yield per area unit is much
higher than Duckweed.
I have mixed Duckweed/Azolla growing quite well.
Most Tilapia growers here use commercial pellet feeds, prices are around
$8 a 25 kg bag @ 27% crude protein.
Tony Cooper
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Subject: Oxygen Cone
From: "Jay Myers"
Date: Fri, 24 Mar 2000 19:54:04 -0600
Chris Weaver
Wondered if you have had any success with a homebuilt O2 cone?
Jay Myers
Panama City Beach, Fl.
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Subject: Re: Oxygen Cone
From: "fkious"
Date: Mon, 27 Sep 1999 18:11:20 -0700
what is a o2 cone
----------
> From: Jay Myers
> To: aquaponics@townsqr.com
> Subject: Oxygen Cone
> Date: Friday, March 24, 2000 6:54 PM
>
> Chris Weaver
>
> Wondered if you have had any success with a homebuilt O2 cone?
>
> Jay Myers
> Panama City Beach, Fl.
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| Message 13 |
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Subject: Re: Any suggestions
From: "Sam Levy"
Date: Fri, 24 Mar 2000 20:47:49 PST
Just how keen on escaping do you find the fish to be? Will they persist in
trying to get through small gaps?
barry,
fish will swim through any gap or hole they can possibly fit through--some
species will even do this to the point where they get stuck in netting large
enough to stick their heads in (i've seen this happen with both hybrid
striped bass & european sea bass--i believe that tilapia are less likely to
get stuck in this manner owing to the conformation of the fish)
>>One possibility I was considering was to fit flexible "flaps" to
>>either>side of the bottom and outside edges of each divider. The flaps
>>would>lie almost parallel to the tank bottom or wall (and might need to
>>be>hinged where they join dividers and sprung to seal them against
>>the>tank - depends on materials used and smoothness of tank).
there are various crowding devices built using this sort of idea--and they
generally work for this purpose--which is to crowd the fish for a limited
time while you preform some chore such as grading, lowering density,
marketing.
>>>Do you (or anyone) know of any (online) growth curves for tilapia
>>>(and>trout)?
on-line you might try the RACs (regional aquaculture centers). i think you
can get to them at:
http: //www.aquanic.org
the southern center has a fair amount of downloadable publications regarding
tilapia. north/north central will probably have something on trout. but
remember, these kind of growth curves will give you a good average for
initial planning but once you've built the system, nothing works like using
your own results
>>For an existing single tank system though, _fixed_ dividers may be
>>a>reasonable upgrade?>
what you're suggesting is taking a single unit and turning it into a
multiple unit--depending on the size and construction material of the
initial tank, it might even be simpler to place smaller tanks (purchased)
inside the existing structure and using the communal drain--some tanks are
constructed in such a way that it would be more effective to simply replace
rather than rebuild.
i believe that this is the kind of problem that begs to have all
alternatives considered on-site with costs of the change and the expected
improvement in production compared carefully before making a final decision.
my own preferences run towards simple, inexpensive, and reversible
(sometimes we decide wrong) for a trial period.i also believe that there is
no one single most correct answer.
sam
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Subject: Re: Belt feeders, etc.
From: "Sam Levy"
Date: Fri, 24 Mar 2000 21:12:16 PST
steve--
the feeder you need will depend on the size and load of your system.
without knowing how much food you need to distribute/day, it's hard to give
you a specific answer.
i've used belt-feeders for commercial style operations (the 12 hour ones
w/supposed stainless steel clockwork mechanism that need to be hand
"charged"). they tend to be inexpensive and reasonably accurate and easy to
use once you figure out how to support them above the tank. they also are
not "controlable"--that is, if critical systems fail while you're not in
attendance, the food will keep on dropping and demanding oxygen that the
backup system may not be able to provide. i also recall a lot of trouble
getting replacement parts when, after 9-15 months of use the mechanical
failures started kicking in.
i personally like demand feeders (if the grow unit is big enough)--again, no
"control"---although the fish will stop feeding after the situation has
really deteriorated (the fish will continue to feed after the point that
you, as the manager, would stop the feeding because your desire is to
conserve the system resources to lower reliance on backup--and lower
risk--while the fish will continue feeding until they've pretty much used up
the system resources). still, demand feeders are the best for allowing the
fish to eat when they want & the quantities that they want.
electric feeders are totally controlable and quite a number are even
reliable. you just have to make sure that you use them to their best
aadvantage & have them set to stop feeding if there is "critical" system
failure (generally, water, electricity, air/oxygen).
there are a number of aquaculture supply houses-w/on-line catalogs & even
the ability to order on-line. look them over & buy the one that you think
is most suited to you--but buy only one for a start--to see if it's really
the answer.
sam
>From: "Steve"
>
>sometimes, it is 12, 14 or even 18 hours between feedings of my Tilapia.
>This includes feeding of the babies (which are suppose to be fed
>6X/day....LOL.)
>
>This greatly reduces the growth of the fish (obviously). When I get home
>and
>feed them, they are just starving.
>
>Anyone have any experience with belt-feeders (or other means of feeding)
>and
>a good (reasonably priced) place to shop for them?
>Thanks as usual.........Steve
>
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| Message 15 |
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Subject: Re: Any suggestions
From: "Sam Levy"
Date: Fri, 24 Mar 2000 21:29:06 PST
>I assume that this is fairly representative (they mention a density of
>80kg/M3 which seems higher than most)?
>
>I was quite surprised when I graphed the average weight and growth per
>day over time. Until week 10 in their table (14 to 16 weeks from
>hatching), growth is slow. Something fairly drastic seems to happen over
>the next 2 weeks then slow steady(ish) increase in rate of change of
>growth which starts to flatten out after about week 24.
barry,
80 kg/m3 is 0.67 pds/gal--and is a high rate--although if it were one tank
out many & market ready (and being sold) at that density, it might be ok.
(jim's comments on feeding quantities for the whole system actually cvers
this uite nicely)
i haven't checked this particular site--but i do suggest you check
literature other than a supplier's web site.
also, if you calculate any of the growth rate parameters (say sgr) for each
week, i think you'll discover that the rate of growth is far greater in the
smaller animals than in the larger ones & that the absolute rate of growth
(grams/day, for instance) will be larger in the big fish.
if you check your feeding, you'll probably find that about 50% of the total
feed will be presented in the final third (time wise) of growth.
sgr can be calculated as: ln(wo/wi)/t
where wo = final period weight
wi = initial period weight
t = time of period (days)
sam
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