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Re: [F] duck weed lowered nitrates



In article <1994Jan18.182245.9696@bme.ri.ccf.org> you write:
>I have gleaned several good bits of help from this group, 
>so here is my contribution.
>
>I have a 29 gallon freshwater tank that has been going for about 
>18 months with 1 large angel, 1 6" pl*co, 1 large gouramie,
>2 dwarf gouramies, 2 swordtails and 2 platies.  UGF with 2 powerheads,
>plastic plants, some algae controlled by pl*co and occasional glass 
>scraping.  20% water changes twice a month with gravel vacuuming.  
>Lighting: one plain old PlenPlax fluorescent. (20-40 watts?)
>
>After loosing 2 dwarf gouramies, I checked the ammonia (0) and 
>nitrates (> 150 ppm!) Started twice weekly 20% water changes and 
>reduced feeding.  This brought nitrates down to 40-50 ppm, where they 
>stayed fairly constant after several weeks.  Maintenance resumed at 
>about 3 times a month.  
>
>I wasn't very happy with this level of nitrates, so I decided I needed 
>something to eat the fertilizer.  I bought a couple of scoops of 
>duckweed, performed daily rinses and complete water changes for a week
>in a quarantine bucket with shop light, then dumped it in the aquarium.
>
>Nitrates are now constant at less than 5 ppm (detection limit of 
>Aquarium Pharmaceuticals dry tab tester.)  I harvest about half 
>the duckweed during each maintenance.  It pretty much covers the 
>surface by the next time.
>
>Simple, easy. Happy fish, happy aquarist.


Article 21922 of rec.gardens:
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From: stngiam@athena.mit.edu (Shih-Tung Ngiam)
Newsgroups: rec.gardens
Subject: Re: Lead from Paint
Date: 28 Aug 1993 22:10:13 GMT
Organization: Massachusetts Institute of Technology
Lines: 26
Message-ID: <STNGIAM.93Aug28181013@primavera.mit.edu>
References: <CCHH1u.9tz@cbnewst.cb.att.com>
NNTP-Posting-Host: primavera.mit.edu
In-reply-to: ebf@cbnewst.cb.att.com's message of 28 Aug 93 19:05:52 GMT

In article <CCHH1u.9tz@cbnewst.cb.att.com> ebf@cbnewst.cb.att.com (eileen.b.fleming) writes:

>   Tomatoes are growing within 6 feet of the house -- 
>   is it possible for the plants to take up the lead
>   from the soil and  deposit the lead in the tomato fruits?

  Fruiting crops are generally less prone to lead uptake than root crops or
leafy vegetables.  However, if the lead level in the soil is very high,
the crops might still contain high levels of lead.  

>   Is there a way to cheaply test for lead concentration
>   in the soil or in the tomatoes themselves?

  The U Mass Agricultural Extension tests soil for lead in addition to
testing for NPK and other nutrients.  The total cost for all the tests
is $7.50 per sample.  They also analyze plant tissue for lead, at a cost
of $10.  Try calling your county Extension Agent (should be listed under
the county government, in the phone book), for details of the procedure
in your area.

Shih Tung
Chem E
Best l'il Tech School
on the Charles