Aquaponics Digest - Wed 03/22/00
Message 1: Re: Duckweed Chronicles
from "TGTX"
Message 2: What do fish eat?
from Carolyn Hoagland
Message 3: Bolting Lettuce
from Tony Cooper
Message 4: re:everything about fish...
from laberge@cil.qc.ca (LABERGE MARC)
Message 5: RE: Bolting Lettuce
from "William G Brown"
Message 6: Re: Bolting Lettuce - Cooling Water
from "John Hite"
Message 7: Re: Bolting Lettuce.
from Robert WALKER
Message 8: Re: Bolting Lettuce - Cooling Water
from "Steve"
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 1 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Duckweed Chronicles
From: "TGTX"
Date: Wed, 22 Mar 2000 03:20:58 -0600
>
> " In clay suspensions, B concentrations of as low as 0.01 mM inhibit
growth
> of L. minor. However, the toxic effect can be neutralized by addition of
> Ca. The highest boron content in the frond (4600 ppm B on a dry weight
> basis) was acheived with 1 ppm B (0.1 mM) and relatively high Ca
> content.....Bolgiano 1979 reports on a more pronounced toxicity of high
> boron concentrations if the Ca concentration is low. Compared with
> Ceratophyllum demersum, L. minor takes up much more boron (up to 45 times)
> (Glandon and McNabb 1978).
>
And another thing about duckweeds and boron, Sam....".In most determinations
boron concentration in L. minor amounts to about 2-3 mg B /gram ash free dry
weight"
That's 2000-3000 ppm Boron on a dry weight basis. Hmmm...is this good?
So, it is possible that, as a potential boron accumulator, the duckweeds
could be used as a "pretreatment" to reduce otherwise toxic levels of boron
in marginal irrigation waters, such as might be found in arid
climates...California, Texas, the Middle East, and so forth...
The toxicity of boron to some vascular plants of economic interest is
interesting in that the trace nutrient requirement concentration and the
toxicity concentration can be so close in value. I think that for some
plants 0.5 ppm Boron is O.K., but 2, 5, or 10 ppm is a no-no......check me
if I am right about those values...just relying on my very faulty memory
here.......
So....any plant, such as duckweed, that could polish marginal irrigation
water down to a non-toxic level of boron would be valuable just for that
purpose alone. Probably already being used in Israel just for that purpose,
am I right?
Ted
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 2 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: What do fish eat?
From: Carolyn Hoagland
Date: Wed, 22 Mar 2000 07:34:59 -0500
Is there a common desk reference that shows which fish or minnow species are
vegetarian, predators, omnivores?
Thanks,
Carolyn
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 3 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Bolting Lettuce
From: Tony Cooper
Date: Wed, 22 Mar 2000 22:06:53 -0800
Does anyone living in a hot climate [e.g. William in Hawaii] have any
recommendations for slow bolting lettuce varieties?
I want to grow lettuce in aquaponics with a good tight head which is the
preferred type in the market here.
Daytime temps get up to 35C.
Also does anyone have a home made water cooling solution? I am thinking
of running the water through a coil of plastic tube placed inside a
water filled chest freezer placed just before it enters the growing
channels.
Thoughts anyone?
Tony Cooper.
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 4 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: re:everything about fish...
From: laberge@cil.qc.ca (LABERGE MARC)
Date: Wed, 22 Mar 2000 09:27:26 -0500
Carolyn there's a book called Scott & Crossman which deal with all
freshwater fish of Canada maybe this could help
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 5 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: RE: Bolting Lettuce
From: "William G Brown"
Date: Wed, 22 Mar 2000 07:20:21 -1000
Sounds like you want head lettuce. If so I can only say that I have had no
luck growing head lettuce. They are much more temperature sensitive and
subject to fungus in hot humid weather. Your best bet would be to try the
summer crisp lettuces that are semi-head lettuce, part leaf, part head and
very tolerant to hot weather. Surprisingly some are low light tolerant,
like Loma which grows good year round. Loma is more leaf than head though.
Since I use rafts I get a 10 degree F reduction in temperature over regular
water temperature which brings me down to a safe temperature for growth.
I.e. down from 88 to 78 degrees. Some people have suggested burying your
pipe in the ground to release heat into the cooler earth. Check the
hydroponics list archives. http://hsa.hydroponics.org
William G Brown mahiwai@cmpmail.con
-----Original Message-----
From: aquaponics
[mailto:aquaponics]On Behalf Of Tony Cooper
Sent: Wednesday, March 22, 2000 8:07 PM
To: aquaponics@townsqr.com
Subject: Bolting Lettuce
Does anyone living in a hot climate [e.g. William in Hawaii] have any
recommendations for slow bolting lettuce varieties?
I want to grow lettuce in aquaponics with a good tight head which is the
preferred type in the market here.
Daytime temps get up to 35C.
Also does anyone have a home made water cooling solution? I am thinking
of running the water through a coil of plastic tube placed inside a
water filled chest freezer placed just before it enters the growing
channels.
Thoughts anyone?
Tony Cooper.
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 6 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Bolting Lettuce - Cooling Water
From: "John Hite"
Date: Wed, 22 Mar 2000 14:08:25 -0600
Hi,
I am new to aquaponics (just joined the list yesterday) but have a little
knowledge of refrigeration so here are my thougts.
Though a chest freezer gets quite cold, it's not a high capacity system.
Usually product is added to a deep freeze a little at a time and since it
is well insulated it can keep up or rather keep the temperature down.
Without having reference data at hand but working from power consumption
assumptions I am guessing the typical large deep freeze (25 cu ft) has a
capacity of about 1500 BTU/hr. One BTU is required to change the
temperature of water 1 degree F. So a deep freeze could chill 1500 pounds
of water by 1 degree per hour. Since water weights 8 pounds per gallon
thats about 188 gallons. I suspect your system has a lot more water in than
this in it. The purpose of refrigeration is to remove heat at one
temperature and be able to disapate it at a higher ambient temperature ( it
also removes moisture). Since you are trying to cool water that is in the
ambient (outdoors) an evaporative cooler such as an air conditioning water
cooling tower may give you better results. Sort of like a swamp cooler.
They work fairly well when the water temperature is higher than the ambient
but I will need to do some research to see how effective it would be when
the water temp is significantly lower than the ambient air temp. At any
rate I am fairly sure it could be more efficient and less costly than
refrigeration if the humidity is not excessive.Chilling water via
refrigeration can be quite costly in operating cost. This is off the top of
my head so to speak. I will try to get you a better answer by Friday.
Plastic tubing has poor heat transfer characteristics but I guess copper is
out of the question where fish are concerned.
If someone else has already covered this I apologize but it seems we
haven't been able to receive inbound mail for several hours.
Best Regards,
John Hite
Tony Cooper wrote:
>Does anyone living in a hot climate [e.g. William in Hawaii] have any
>recommendations for slow bolting lettuce varieties?
>
>I want to grow lettuce in aquaponics with a good tight head which is the
>preferred type in the market here.
>Daytime temps get up to 35C.
>
>Also does anyone have a home made water cooling solution? I am thinking
>of running the water through a coil of plastic tube placed inside a
>water filled chest freezer placed just before it enters the growing
>channels.
>
>Thoughts anyone?
>
>Tony Cooper.
>
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 7 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Bolting Lettuce.
From: Robert WALKER
Date: Thu, 23 Mar 2000 12:40:55 +1000
Hi,
I live in Australia, in an area which has high extremes, very
cold in winter (avg 9c in the day), and Hot in summer (Avg 30+).
I have been mucking about with Fish and Hydroponics, and dont
have much experience with "most things", However, with my fish
being in a garden shed over summer the temp got to 50c+ in the shed
and thoughts of trying to keep the water cool came to mind.
My thoughts, although not practiced, was to look at a home made
heat pump. Basically I though that by placing "polypipe" into
the ground at say 2 feet could be away of reducing the heat, after
all it takes some time for the ground to warm up compared with
water, and the conduction process could be improved if using
stainless steel 316 grade - I believe!?! Thus if the heat sink was
placed in an area which did not receive a lot of sunshine thus
did not heat up due to radiation, then you could come up with
a cheaper cooling alternative??
Just some thoughts,
Robert.
.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
| Message 8 |
'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
Subject: Re: Bolting Lettuce - Cooling Water
From: "Steve"
Date: Wed, 22 Mar 2000 21:05:00 -0600
Hi John,
Welcome to the list.
Steve
----- Original Message -----
From: "John Hite"
To:
Sent: Wednesday, March 22, 2000 2:08 PM
Subject: Re: Bolting Lettuce - Cooling Water
>
> Hi,
>
> I am new to aquaponics (just joined the list yesterday) but have a little
> knowledge of refrigeration so here are my thougts.
>
> Though a chest freezer gets quite cold, it's not a high capacity system.
> Usually product is added to a deep freeze a little at a time and since it
> is well insulated it can keep up or rather keep the temperature down.
> Without having reference data at hand but working from power consumption
> assumptions I am guessing the typical large deep freeze (25 cu ft) has a
> capacity of about 1500 BTU/hr. One BTU is required to change the
> temperature of water 1 degree F. So a deep freeze could chill 1500 pounds
> of water by 1 degree per hour. Since water weights 8 pounds per gallon
> thats about 188 gallons. I suspect your system has a lot more water in
than
> this in it. The purpose of refrigeration is to remove heat at one
> temperature and be able to disapate it at a higher ambient temperature
it
> also removes moisture). Since you are trying to cool water that is in the
> ambient (outdoors) an evaporative cooler such as an air conditioning water
> cooling tower may give you better results. Sort of like a swamp cooler.
> They work fairly well when the water temperature is higher than the
ambient
> but I will need to do some research to see how effective it would be when
> the water temp is significantly lower than the ambient air temp. At any
> rate I am fairly sure it could be more efficient and less costly than
> refrigeration if the humidity is not excessive.Chilling water via
> refrigeration can be quite costly in operating cost. This is off the top
of
> my head so to speak. I will try to get you a better answer by Friday.
>
> Plastic tubing has poor heat transfer characteristics but I guess copper
is
> out of the question where fish are concerned.
>
> If someone else has already covered this I apologize but it seems we
> haven't been able to receive inbound mail for several hours.
>
>
> Best Regards,
>
> John Hite
>
>
>
> Tony Cooper wrote:
> >Does anyone living in a hot climate [e.g. William in Hawaii] have any
> >recommendations for slow bolting lettuce varieties?
> >
> >I want to grow lettuce in aquaponics with a good tight head which is the
> >preferred type in the market here.
> >Daytime temps get up to 35C.
> >
> >Also does anyone have a home made water cooling solution? I am thinking
> >of running the water through a coil of plastic tube placed inside a
> >water filled chest freezer placed just before it enters the growing
> >channels.
> >
> >Thoughts anyone?
> >
> >Tony Cooper.
> >
>
>
|
