I write to you from Singapore, on the other side of the world. I have a 20-year old 50 metric ton
koi pond. This volume includes two 4.30 tons aerobic biological filters fed separately by two 6-inch bottom drainpipes
from the main pond. The 50 tons of water is turned over every hour.
I wish to convert one of the
filters to provide anoxic filtration. The biocenosis basket it is said to
contain “cat litter”, a material I am not familiar with. What is its chemical composition?
Is it made from burnt clay comprising mainly calcium carbonate?
It is said that the anoxic
filter will not clog. However I presume there will be a bed of fine sediment at
the bottom of the filter, which will have anaerobic reaction if not flushed on
a regular basis. Both the filters have pre-settlement chambers to remove the
larger solid waste. In the biocenosis basket please advise what volume of cat litter
against what volume of Laterite. Can you email me a sketch to illustrate the construction?
I shall be pleased if you would advise if my proposal is feasible.
Thank you
Keen Wong
Dr. Novak's reply:
I thought this E-mail that I
received today would be great ice breaker because it looks like he uses a bog
filter of some sort. He has 13,300 US GAL that’s what 50 metric tons comes up
to, and I may be reading this wrong but also he’s using 8600 lbs of aerobic
biological filter medium of some sort. With that much weight I would assume its
pea-gravel and not just K-1.
When I talk about cat litter or Oil-Dri (that’s
used for it capillary action in picking up liquids) you wouldn’t think I’m
talking about nuclear waste or some other esoteric material. In the USA cat
litter from Wal-Mart is very easy to buy and it’s cheap, but in other countries
I have found that plain old baked, low dust cat clays that are the non-clumping
form are not so easy to find.
Dr. Franco, he
did the Anoxic Filter test from Italy, had to travel to the UK and buy tons of
the stuff because in Italy they had none or not the right kind that would
suffice for the biocenosis baskets. Because I’m not an expert in cat litter
from all over the world I can only tell you what I know.
Finding alternative brands outside the US like
Kitty Litter by Wal-Mart will take some experimenting on your part because very
few makers of cat litter will display the ingredients on the outside of the
bags or boxes that it comes in. Look for cat litter clays that have been fired
at high temperatures because unfired clay granules swell and clump together
when wet and crumble when dried, they will surely state it on the box or bag.
It is very important that any cat litter clay granules you use keep their
structure indefinitely. I show photos of 20-year old cat litter that still
holds it structural integrity even when cleaned. Testing clay product for its
ability to retain its structure, first soak some of it in a glass of water for
24-hours and check that the granules do not break down.
The photo above is of 20-year old cat litter.
Bentonite: Do not use
• Clumping cat litters are made of Bentonite clay, which sticks together
when wet. The bentoniteis usually mixed with quartz and diatomaceous
earth, which are absorbent.
Other Clays:
• Various types of clays are used for non-clumping cat litters. Zeolite,
diatomaceous earth and sepiolite are common.
• (Only
use clay –Attapulgite-that has been mined from the earth, clean, baked, and
pulverized such as Kitty litter.)
Making up biocenosis-pots for filtration and
plants is really quite simple. The supplies you will need are large planting
baskets (11" x 11" x 7" or 14" x 14" x 10"),
kitty litter (with no additives just plain clay), and Laterite that will be for
the substrate. Laterite is a highly weathered remnant of volcanic rock
(weathering implies exposure to tropical temperatures, precipitation, and
forest derived humic acids over geologic time). Very rich in iron, and
Manganese (iron is needed for plants to make chlorophyll). Taking a plant
basket as shown in illustration #1 then
filling it with Kitty litter, make sure you leave a small impression in the
center of the basket. Take about half cup for smaller baskets and one and a
half cups for larger baskets of Laterite and pouring it into the center of the
basket then mixing the Kitty litter and the Laterite in the center of the
basket.
Now place only one layer of pond pebbles on top, this is to keep the
Kitty litter from floating up after submerging it into the pond. Instead of
using pond pebbles, you can also use a black craft screen on top and wire-tie
it to the basket. The Laterite will help the bacteria grow in its early stages,
once the bacteria becomes established, it will be less dependent upon the iron
in the Laterite for growth. The good thing about the planted basket is it will
take years before clogging with organic matter (it may take 20 years or
longer). You will use the same procedure for the planted biocenosis-baskets,
but you will not use the black craft screen on top of this basket only the pond
pebbles.
I hope this helps,
Kevin
Anoxic Filtration Book... Still free on Apple's iBook store
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