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Substrate Analysis

Contents:

  1. Substrate research
    by "Jamie Johnson" <jjohnson/davisfloyd.com> (Tue, 3 Aug 1999)
  2. Cation Exchange Capacity
    by "Jamie Johnson" <jjohnson/davisfloyd.com> (Wed, 4 Aug 1999)
  3. Re:Substrate Gold ingridients
    by "Robert H" <robertpaulh/earthlink.net> (Sat, 22 Apr 2000)

Substrate research

by "Jamie Johnson" <jjohnson/davisfloyd.com>
Date: Tue, 3 Aug 1999

Hi All,
It's been kinda slow this afternoon at work, so I started a little 
project I've been curious about for some time now. My tanks use a 
kitty litter/sand substrate and I've never had any complaints. First 
off, I don't move the big plants around to disturb anything serious. 
And, second, I don't have my 'mining cichlids' in those tanks, 
either. My cichlid tank is about to undergo big changes, I'm 
replacing the gravel bed with Fluorite. Being born with a very 
stubborn, analytical brain, I had to research. I was very curious to 
find what my substrates were made of, elementally. Since I work at 
a lab and do trace metal analysis, I knew it was only a matter of 
time before I got the best of myself. 

I did analysis on 3 samples: Fluorite, Wal-Mart Special Kitty litter, 
and soil from my garden. 1g of dry sample was pulverized by a 
mortal/pestal and digested according to Method 3050B EPA Soil 
method. *Disclaimer of method - This is not a total digestion. It is a 
very strong acid digestion that will dissolve almost all elements that 
could become "environmentally available". By design, elements 
bound in silicate structures are not normally dissolved by this 
procedure as they are not usually mobile in the environment.* This 
is still a VERY good representation of what is in the sample, as we 
use it daily for all kinds of solid samples. A Hydrofluoric acid 
digestion in more complicated, but more geologically correct, as it 
gets EVERY element in solution. I will do the HF digestion later to 
compare results. Should be quite interesting. Here's what I got:

Element            Soil (mg/kg)    Litter (mg/kg)   Fluorite (mg/kg)       

  Al                       5700              6000               6800
  As                        <                  8.1                 11.3
  Ba                       156               11.6                133 
  Be                       0.2                 0.5                 0.3
  Ca                      5800             14300               530
  Cd                       0.6                 2.4                  <
  Co                       2.6                 2.7                 3.4
  Cr                        10                  30                  6.2
  Cu                       73                 12.6                13.8
  Fe                     11500             14500              9610
  K                        433                2200               1700
  Mg                     1000               3760               1490  
  Mn                      136                47.5                85.5
  Na                       570                395                 444
  Ni                        4.1                 21.1                8.0
  Pb                       218 ?             9.3                  5.4
  V                         24.5              12.3                 8.8
  Zn                       248                70.5                33.5

Three things caught my eye. First, where did my garden get Pb 
from?? It's an old house and the garden in right against the wall, so 
maybe years of lead paint leaching from rainwater into my soil. I 
don't care, the veggies are delicious! Second, the As level in 
Fluorite. It's addressed in their website, it doesn't leach out and is 
no cause for concern.  And, third, does my cat know he is standing 
in Cd laced clay? I don't know where it came from, either, but 
again, it doesn't leach out. My water tests sooo clean from my 
tanks, and the only thing that ever shows is the things I add. I was 
real surprised to see how dynamic my litter was. It's loaded with all 
kinds of good stuff, plenty of Ca, Fe, K, and Mg. The soil looked 
good, too, except for the lead. The Fluorite was the least reactive of 
the three. It's hard as hell to grind up and just sits in the acid, 
where the other two fizz and bubble, mainly because of the Ca 
compounds and the organics in the soil. Small amounts of the litter 
and soil went into solution, but I think all of the Fluorite stayed in 
the beaker. It's like a crumbled brick sample. 
I've got to admit I'm impressed by them all. I would've bet any one 
of them would have lacked something important, but they're all 
comparatively good. I didn't test my gravel, probably something like 
950,000 mg/kg SiO2 ;-). I hope someone finds it all interesting. 
Now, it's time to wash and rinse 45lbs of Fluorite. 

Jamie
Jamie Johnson
Greenwood, SC
jjohnson@davisfloyd.com
jjirons@greenwood.net  (home)


Cation Exchange Capacity

by "Jamie Johnson" <jjohnson/davisfloyd.com>
Date: Wed, 4 Aug 1999

Hi All,

After determining the total metals of my garden soil, kitty litter, and 
Fluorite, I still had a curiosity about the CEC. I know over the past 
year, the APD has had several discussions about CEC and 
substrates. I know Steve P. gets pretty excited when it comes to 
talking about CEC, so I thought I would find some hard values to 
discuss.

CEC, for those who may not understand, is defined as the sum of 
the exchangeable cations of a soil. It's expressed as 
milliequivalents or me. per 100g of soil. Soils most often vary from 
<1.0 to >100 me./100g. It's a reversible chemical reaction. Cations 
are held on the surface of soil minerals and held within the crystal 
framework of some mineral species. Cations are also a part of 
certain organic compounds. All these cations can be reversibly 
replaced by those of salt solutions and acids.
I used EPA method 9081A CEC of soils by sodium acetate. A 
sample is mixed with an excess of sodium acetate solution, 
resulting in an exchange of the added sodium cations for matrix 
cations. Subsequently, the sample is washed with 99% isopropyl 
alcohol. An ammonium acetate solution is then added, which 
replaces the absorbed sodium with ammonium. The conc. of 
displaced sodium is then determined. From this, it's run through 
half a page of calculations to get an answer of me./100g soil. 
Here's what I got:

CEC (me./100g)              Matrix
- -----------------------------------------------------
   <0.1                         Clean sand
    24.3                            Soil
    27.0                           Litter
    1.7                            Fluorite
          
As I expected (hoping for, anyway) the sand was <0.1 me./100g. 
There wasn't any Na to be found in the sand sample. There aren't 
any binding sites for cations (minute to nil) on sand grains. The soil 
had a thin layer of silt (1/3 of sample) present in the wet sample, 
so I expected it to have a good CEC. There was also some small 
pieces of organic matter mixed in, also suggesting another good 
binding site. There was ~280ppm Na leached from the sample, 
which calc. to ~24.3 me./100g. The kitty litter held the most 
promise for me. It's a small sized clay/silt and those usually have 
good CECs. The sample leached ~310ppm Na, which gave the 
highest CEC of 27.0 me./100g. The Fluorite didn't fare too bad, but 
it only leached ~19ppm of Na, leading to a low CEC value of 1.7. 
It's easy to understand, since Fluorite doesn't break down to 
expose the millions of binding sites found in clays. I would dare 
say a lot of the laterite sold for aquarium use has a CEC value 
close to the litter, probably higher for finer, more organic laterites. 
Now I'm curious what kind of soils have the >100 values. I could 
see a DI system's resin bed as being pretty high, but a natural 
source is probably pretty rare. We've tested soil from all over, 
mainly the first foot of depth, and the litter holds the record for the 
highest I've seen. Most red/orange clays (our area) have low CECs.

Jamie




Jamie Johnson
Greenwood, SC
jjohnson@davisfloyd.com
jjirons@greenwood.net  (home)


Re:Substrate Gold ingridients

by "Robert H" <robertpaulh/earthlink.net>
Date: Sat, 22 Apr 2000

>>Karl Schoeler recent gave Robert H. the composition (but not the
percentages) of his Substrate Gold and Natural Gold (see
http://www.aquabotanic.com/plantfer.htm). Perhaps Karl would tell us what
prompted him. <<

Did Karl already answer this? If so I missed it..so pardon any redundacey...

Actually the info from that chart I got from his WEB site, and at the time
he didnt disclose the %. But recently he has...he emailed me a complete
analysys a couple of weeks ago, and I think I already posted it here in a
response to a fertilizer question. I have the info listed on my for sale
page, but havnt updated my chart yet. I dont know what prompted Karl to
disclose it, except that he wanted me to sell his product! I have to say
that this new info has put to rest previous reservations I had about the
product..natural gold now looks just as attractive to me as Mastergrow.

Here it is:

Substrate Gold - :
Nitrogen                 .01%
Phosphorus            .041%
Potassium              .01%
Boron                     .0091%
Molybdenum        .0000187%
Calcium                  .3815%
Magnesium             .1361%
Copper                   .001754%
Iron                       3.37%
Manganese              .016%
Zinc                        .001236%
Sulfur                      .01%
Natural Gold - Water Column Fertilizer:
Nitrogen                   .11%
Phosphorus              .01%
Potassium                .19%
Boron                 .0009692%
Molybdenum          .000091%
Calcium                    .028%
Magnesium               .0121%
Copper                  .0007075%
Iron    EDTA              .2994%
Manganese           .0002617%
Zinc                       .0005427%
Sulfur                        .10%

Robert Paul H
http://www.aquabotanic.com


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