Aquaponics Digest - Mon 03/30/98
Message 1: Re: Safe plastics?
from "Sandy S. Brown"
Message 2: Re: Safe plastics?
from "William S. Snyder"
Message 3: Re: Safe plastics?
from Gordon Watkins
Message 4: PVC Pipe Safety
from Gordon Watkins
Message 5: DO meters
from Chad Kruger
Message 6: New aquaponic garden questions
from "Jim S"
Message 7: Re: DO meters
from morhunt@sprint.ca
Message 8: Re: DO meters - Query
from Spivas
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Subject: Re: Safe plastics?
From: "Sandy S. Brown"
Date: Mon, 30 Mar 1998 07:09:53 -0500
Gordon,
You stated on Saturday
>I have seen some indication that long-term use of pvc pipes can leach
>toxins in closed systems.
I find this to be particularly unsettling, since the PVC we use in our
system is labeled "well casing," and is the same thing that provides all of
our household water from our 400 foot-deep well. This is the standard
white PVC, but I know that it also comes in a grey formulation. Do you
have any feel for whether there is a difference in toxicity by formulation?
Sandy
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Subject: Re: Safe plastics?
From: "William S. Snyder"
Date: Mon, 30 Mar 1998 08:41:38 -0500
Sandy S. Brown wrote:
> Gordon,
> You stated on Saturday
> >I have seen some indication that long-term use of pvc pipes can leach
> >toxins in closed systems.
>
> I find this to be particularly unsettling, since the PVC we use in our
> system is labeled "well casing," and is the same thing that provides all of
> our household water from our 400 foot-deep well. This is the standard
> white PVC, but I know that it also comes in a grey formulation. Do you
> have any feel for whether there is a difference in toxicity by formulation?
>
> Sandy
Recently I queried several professional listserves about the possibility of
pvc leachate (a friend of mine is beginning some rather delicate planktonic
research and wanted to dismiss as many biases as possible).
The responses indicated that although there is some degree of leachate from the
pvc, it is minimal, and decreases over time. Although exposure to UV light
enhances the mobilization of the vinyl chlorides, our water contact is on the
inside of the pipe, hence...no problem.
My recommendation is, don't sweat it. Make sure that your pvc is well rinsed,
especially if you have used any solvents or cleaners. Otherwise, I think there
are many greater sources of toxicants we can spend our time worrying about.
Bill
--
> > > > > > > > > > > > > > > > > > >
William Snyder, Aquaculture and Aquatic Sciences
State University of New York - Morrisville
Morrisville, New York 13408
tel: 315-684-6237 fax: 315-684-6125 in%: SnyderW@Morrisville.edu
web: www.snymor.edu/pages/aquaculture/
"Opportunity is missed by most people because it is dressed in overalls and
looks like work." --Edison
> > > > > > > > > > > > > > > > > > >
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Subject: Re: Safe plastics?
From: Gordon Watkins
Date: Mon, 30 Mar 1998 08:38:48 -0600
Sandy,
I believe it's really only a problem with delicate organisms in closed,
recirculating systems where toxins may be tend to accumulate over time.
In flow through systems, such as used for household water, it's not a
significant problem, otherwise I don't guess pvc would be approved for
potable water.
Gordon
Sandy S. Brown wrote:
>
> Gordon,
> You stated on Saturday
> >I have seen some indication that long-term use of pvc pipes can leach
> >toxins in closed systems.
>
> I find this to be particularly unsettling, since the PVC we use in our
> system is labeled "well casing," and is the same thing that provides all of
> our household water from our 400 foot-deep well. This is the standard
> white PVC, but I know that it also comes in a grey formulation. Do you
> have any feel for whether there is a difference in toxicity by formulation?
>
> Sandy
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Subject: PVC Pipe Safety
From: Gordon Watkins
Date: Mon, 30 Mar 1998 08:44:48 -0600
Here are a couple of clippings from my files from aqua-l that may shed
some light on the discussion of PVC piping.
Gordon
(snip)
PVC plastic contains a variety of compounds, the combination of which
will vary from manufacturer to
manufacturer. Most of the PVC will contain lead and TBT ( tributyltin),
TBT is the active ingredient in
marine anti fouling paints. The product has now been banned because of
its extreme toxicity to
invertebrates and bivalves. If PVC is used in recycle system the toxic
will be bio accumulated in the
cultured species. As a company we would never under an circumstances use
PVC in recycle systems.
As a much better alternative to PVC we use ABS or MDPE plastics for
pipes.
(snip)
From: GRANT MOVOLD
To: "'patterrn@tuns.ca'"
Subject: REF ; PLASTIC PIPE TOXICITY
Date: Thu, 6 Nov 1997 16:09:42 -0500
E-MAIL RESPONSE
TO ; DICK PATTERSON AQUACULTURAL ENGINEERING RESEARCH ASSISTANT
DALTECH , DALHOUSIE UNIVERSITY , NS.
EMAIL (SMTP:patterrn@tuns.ca)
REF ; PLASTIC PIPE TOXICITY
Thanks for your E-mail requesting information regarding the leaching
of toxic compounds from plastic pipe systems .
The focus of the study as well as the questions must be defined to a
much smaller focus or selection of plastic materials . There are
approximately 12 separate plastic materials available for the
fabrication of products which can be used in the Aquaculture
industries .
Each of the production processes used to manufacture the end
products require additives in order to process the raw materials
into a finished product . As the finished product is generally used
in an industrial application where very strong chemicals are present
the concern is not toxicity but durability under very aggressive
conditions .
The general use of PVC pipe and fittings has gained favor in most
industries such as yours due mostly to its price and availability .
Also the product has gained acceptance as a fast product to install
and handle on site. This product can introduce toxins of the nature
you outline from the mold release agents used during production as
well as some trace eliminates on an ongoing basis from the base
material itself . The most likely area of contamination is in the
area of the glue joints and the cements used in the assembly .
Please note there are as many as 20 possible cements that could be
used for PVC pipe joints and each has its own chemical make- up .
I feel that in order to evaluate this problem your people have to
first address the raw materials your application can afford to use
and to what degree they want to go to prevent the leaching or
contamination of the aquatic cultures you are growing . I know very
little about marine life and their tolerances to specific toxins but
I suppose that each species has a tolerance level which may require
the testing of many plastics materials . This will establish a
plastics material match to a species tolerance level .
Fabricated Plastics offer many plastics products which address the
issues of contamination buy such industries as ULTRA PURE WATER ,
SEMI CONDUCTOR MANUFACTURING and PHARMACEUTICAL products.
The materials used by these industries are proven to perform
without contributing any trace elements into the product stream .
The prerequisite to all the materials used throughout these
industries is that they have tested and approved only specific
materials , grades and manufactures .
THEY PRE SELECT ALL ASPECTS OF PRODUCT AS WELL AS THE SUPPLIER .
The general range of plastics product available which we offer to
the above industries are as follows in order of their resistance to
leaching into the product stream .
PVC , Polypropylene , Polypropylene (FDA Approved) , Polyethylene ,
PVDF (Kynar )
I have outlined Polypropylene as we offer Three options in this line
which are affordable as well as available with a full line of valves
and fittings which complete the system in matched materials.
I have forwarded you a copy of the Project Profile on an application
which took our abilities to the ultimate extreme and we actually had
raw materials formulated specifically for this one project to
resolve a problem which would only apply to this one customer .
I would be pleased to forward information to your people on any
specific products they request . The FABCO BUYERS GUIDE HAS BEEN
ISSUED as a general guide to what is available .
Look forward to working with you in the future .
Ted Gibbs
Technical Sales Representative
( tgibbs@fabricatedplastics.com )
Richard N. (Dick) Patterson, P.Eng.
Aquacultural Engineering Research Assistant
Agicultural Engineering Department
DalTech, Dalhousie Unversity
PO Box 1000, Halifax, NS, Canada
P: (902) 420-7862 F: (902) 423-2423
H: (902) 435-3665 Email: patterrn@tuns.ca
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Subject: DO meters
From: Chad Kruger
Date: Mon, 30 Mar 1998 10:17:27 -0800
Does anyone know of a good DO meter - that is not of the membrane
sort? Or does everyone find a simple chemical test more efficient and
accurate?
Chad Kruger
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Subject: New aquaponic garden questions
From: "Jim S"
Date: Mon, 30 Mar 1998 13:28:48 -0600
I about to get life somewhere close to normal here again and am getting
down to the wire on installing my new aquaponic garden system. As things
stand my growout tank will be stabilised concrete composed of 4 runs 4' x
20' by 3' deep. I'm using a modified version of Ian pentagonal polyhouse
design over the new fish runs. Also, I'm in the process of converting 24' x
48' of greenhouse area to aquaponic planting area.
I guess my real question should be: During the time I'm waiting to have a
good enough feel for the tilapia to count on them supplying food for the
plants, could I grow out a different variety of fish in the tanks (in
addition, say to a few hundred talapia) to make up for the lower fish/ bed
volume ratio? I could use the other tanks to grow out some crappie or bass
for personal stocking efforts, while I wait on the first batch of talapia
to grow up, or me learn to grow them. ;)
I'm just not ready to jump into 5-7000# of tilapia right from the start,
but I need those beds growing something from the start.
Jim S.
PS: anyone else running a Pay 'by the day' or 'by the pound' fish pond'?
Ever thought about stocking it with big, if not quite trophy sized fish?
We've done very well with catfish, but I want to try bass and crappie now.
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Subject: Re: DO meters
From: morhunt@sprint.ca
Date: Mon, 30 Mar 1998 19:42:56 -0400
Hi Chad, I use an Oxyguard Handy Mark 111, made by Point Four Systems.
It's a pricey meter (about $1200 Canadian) but it is one of the most
valuable tools I have. The membrane is very easy to change, much easier
than the older YSI meters. I believe LaMotte and Hach have wet kits for
measuring D.O. The best choice for you will depend on your requirements.
If you are producing fish for your own consumption, a LaMotte or Hach kit
will do the job. If you are planning on commercial or semi-commercial
production I would opt for a good D.O. meter. It is more accurate and much
more efficient.
Cheers
Carl Huntington
Fish Health Tech.
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> From: Chad Kruger
> To: aquaponics
> Subject: DO meters
> Date: March 30, 1998 14:17 PM
>
> Does anyone know of a good DO meter - that is not of the membrane
> sort? Or does everyone find a simple chemical test more efficient and
> accurate?
> Chad Kruger
>
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Subject: Re: DO meters - Query
From: Spivas
Date: Mon, 30 Mar 1998 23:10:39 EST
The Hach test for DO is based on the Winkler classic test. (Hach is a
company, with no endorsement implied - just that the DO test works very well
if you follow the instructions). As someone else has noted, LaMotte makes a
similar test.
The Hach version is a modified mini-Winkler, that has been in use for at least
20 years. The Winkler is the standard by which the membrane probes are
tested.
The Hach version works well, although it takes a few minutes. If you need
address and product numbers, say so, and I'll bring the catalog home from work
and fire the 800-number for the company out over the list serve, with the
important numbers.
The test is very portable - I brought one to Africa many moons ago. It worked
swell!
And the cost is less than $100. What's your need? If it's really important
to test DO, _fast_ then go with the electronic. If you are just interested,
go with the wet test.
Steve Ivas
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