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Scheel Letters: General Information on Peat
Courtesy of
ARK - Arizona Rivulin Keepers
The Scheel Letters, No. 20
General Information on Peat
Early in 1958 I prepared a small article on the Use of Peat and Peat moss
in Aquarium Keeping and sent it to a few foreign aquarists with whom I cooperated
in the Killie question. Well, I certainly mailed all copies and did not reserve
any for the possible production of more copies and as more aquarists since then
have joined us in the mailing of eggs and keeping of killies, possibly more information
of the peat as a whole might be of interest. Recently I made a small article on Peat
for Dansk Akvarieblad as an opening of a series of articles on this particular
question in the common aquarium keeping and in particular for aquarists who want
to establish a so-called rainforest aquarium.
Peat and Peat moss is a mass formed by more or less decomposed and stabilized
remains from sphagnum mosses and/or other mosses and bog-vegetation. In this way nature
stores rather many valuable nutritious matters that soon or mostly later might be
used by plants. Peat contains many plant nutrients which in the free form are only
present in limited amounts in nature, such as carbon (C), nitrogen (N), phosphor (P),
sulfur (S), and potassium (K) and also the unlimited nutrients hydrogen (H) and
oxygen (O). Normally peat has 55-56% carbon, 33% oxygen, and 3-6% nitrogen.
Iron (Fe), calcium (Ca), and magnesium (Mg) are found in the peat also. Peat normally
also might contain lots of trace elements once taken up by the living plants or later
by the peat itself such as silver, gold, beryllium, zinc, cadmium, scandium, thallium,
germanium, tin, lead, arsenic, manganese, cobalt, and nickel. The contents of metallic
elements vary greatly depending on the conditions under which the peat has been formed
and the later contact with the surrounding waters.
Peat and peat moss in nature contain some anti-biotics such as penicilin,
streptomycin, aureomycin, and alike and the rather strong bacteria killing (or inhibiting)
power which is ascribed to peat and bog waters might come from such anti-biotics.
After all, in my opinion, the anti-bacterial power very often increases during the
use of a certain peat sample as bottom layer in tanks (in 1950 I set up my first
rainwater tank, since then more and more of my tanks were changed into this type
and since 1954 all 40-60 tanks are of this type (except one pit-coal tank in use
since 1954). This might lead to the conclusion that certain anti-biotics producing
organisms establish themselves in the bottom layer and are sending anti-biotics out
into the water. In my opinion, the brown color of the aquarium water also has only
a minor influence on the bacteria inhibiting power, but also that something points
in the direction that the bacteria inhibiting power is removed together with the brown
color if you use active charcoal in filters for removing of the brown color of the
water. Also some hormones are present in the natural peat and possibly certain sexual
hormones present in the peat (oestrogenes etc.) might be of great importance in the
breeding of certain rainforest fishes such as Nannostomus trifasciatus, Carnegiella
strigata, Acanthophthalmus kuhli, etc. Did you ever read the interesting articles
of Profesor Stolck in the Dutch aquarium magazine "Het Aquarium"? Stolck added urine
from pregnant women to the water of the tank in which he had pairs of very difficult
rainforest fishes (0.5 ccm per liter) and after some time the females were ripe and
he had good spawnings when he removed the breeding pair to urine free waters. No
doubt certain sexual hormones are formed during the decomposition of leaves etc.
on the dry ground before the rainy season and these are washed out from the decomposing
vegetable matters by the rain and force the female fish to produce eggs just at the
right time for breeding. Good breeding results in rainforest tanks might, in some
way, be brought about by some hormones in the peat.
Vitamins are also present in peat: A, B, D, F, K, etc. I do not know if
they play any role in connection with the aquarium keeping.
Just like active charcoal, peat will willingly take up certain high molecular
compounds by absorption. Most of the dyes commonly used against diseases in fish,
such as trypaflavine, acriflavine, euflavine, rivanol (all are acridin compounds)
and also gentianviolet and methyleneblue are absorbed very quickly, making the
treatment of many common diseases in fish very difficult or impossible in rainforest
tanks. No doubt also quinine is taken up in just the same way. All these dyes are
nominal "cations" as they are "chlorides", "sulfates" or "lactates". No doubt some
of the waste products from the fishes are taken up and stay fixed to the peat for some
length of time before they decompose into more simple compounds that cannot be fixed
by the peat.
Peat has a more or less pronounced power of exchanging ions. The cation
exchanging power reminds one of the so-called "weak cation exchanging resins" which
might be buffered to a certain pH value. Peat that in nature is not in contact with
natural surface waters seems to be charged with many hydrogen ions and therefore will
make the aquarium water very acidic. Peat (like the common Danish form) that in
nature has been in contact with the surface waters (alkaline) a long time ago has
exchanged the hydrogen ions for higher metallic ions and therefore such peat will
not change the pH of the aquarium water. "Discharged" peat might be "regenerated"
in the way as cation exchanging resins. The cation exchanging capacity is rather
limited compared with the resins. The anion exchanging power is present, but not
very well known.
Peat takes up any copper that comes into the water and the taking up takes
place very quickly. This might be taken into consideration, for example, when
you use copper against hydra or oodinium (velvet). The taking up of this cation
no doubt takes place in some ion exchanging action (Cu normally has two positive
charges). In this way peat is a protection against most poisonous metals that
come into the water - for example, from corrosion of the stainless steel or other
metals in contact with the water. This taking up of the heavy metallic ions is
limited. If the water in such tanks later on is made more acidic probably poisonous
ions might enter into solution. Therefore perhaps such peat should be taken out of
the tank and given a "regeneration" using some strong mineralic acid (10% hydrochloric
acid HCl).
Peat in contact with water very soon will give away some brown color that
will make the water more and more brownish. If you add peat to 3 samples of water:
first using distilled water, second using common hard tap water and third using distilled
water with soda added, you will find that after a certain time the first one will be
less colored than the second and the second one less colored than third one. The
brown color comes from certain humates in which metallic ions play a certain role.
Humates from calcium and magnesium (Ca2+ and Mg2+) are less soluble than humates
from potassium and sodium (K+ and Na+). Also the pH of the water (or the presence
of salts from carbonic acid) play a certain role in the way that alkaline waters
will be colored much more than acidic waters. Once I used to boil samples of peat
with a rather strong solution of soda (Na2CO3 x 10 H2O) and that way I got a solution
which was as brown as a good coffee. This solution has been used by aquarists and
dealers who have added the black liquid to their tanks and claimed to have good
results in common "sand-tap water-tanks". A sample of peat treated like this will,
after some washing to remove the soda, give less coloring when used in a tank as
bottom layer. The brown color of the water in the rainforest tank is very stable
and not easily removed. If you have a good supply on distilled or demineralized
water, perhaps the best way will be to change the water if it gets too brown. You
might use a filter filled with activated charcoal, but do control the outflow when
starting the filter. If the pH of the outflow is too high (often above 8..2!!) you
will have to wash the charcoal (we use the common alkaline tap water for these washings
and have the tap water very slowly running through the filter for about 24 hours).
Charcoal takes up the brown color rather slowly, but after some days of filtering
you will realize good results and all color might be removed using this material.
Such filters on the other hand have very high capacities indeed. I also tried the
"Decolourite", a particularly weak anion exchanging resin made by the Permutit Co.
that might be regenerated using a weak solution of soda in water. However I did
not find this material to be superior to the common activated charcoal, but it is
still in use in a column placed after the outflow of a weak cation exchange resin
(Amberlite IRC 50) where it is used to remove any color (and high molecular compound)
present in "old aquarium water" which is treated because of too high pH values.
Decolourite has a particularly high capacity when the water is acidic. Many years
ago I also used activated aluminium oxide (the gamma modification commonly used for
chromatography) to take up the brown color. This material I regenerated using hot
hydrogen peroxide (H2O2) but also this material (very expensive too and not easily
supplied) is not superior to charcoal.
Aquarists normally will not permit the water in their tanks to become too
brown because this color to a very high degree steals away the light and plants
will suffer. Also the brown color will decrease the green and blue colors of the
fish, whereas in a pleasant way it sets off the yellow-orange-red colors of the fish.
And after all as the brown color possibly does not play any important role in the
rainforest tank, why not remove it.
