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