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An argument settled at last
Before my recent business trip to Europe, I did some
experiments with substrate heating coils. Since I was going
to have plenty of free time on the airplane on the flights
to and from Brussels, I took along my notes and wrote up the
results on my laptop. The results were so intriquing that I
had to post this right away, even though I just got off the
plane a few hours ago.
George Booth
Ft. Collins, Colorado
+--------------------------------------------------------+
| Conclusive Proof: Substrate Heating Coils Really Work! |
+--------------------------------------------------------+
BACKGROUND
Various things recently have provided the opportunity and
impetus to dive into substrate heating coil experiments.
(1) There has been a plethora of disparaging remarks from
certain APD-ites about the lack of scientific evidence that
heating coils do anything more than waste electricity. The
gods of Dupla apparently don't care to toss their 2 centi-EUs
into the fray so I've been challanged to present some evidence
of my own.
(2) We have an old 29 gallon tank that used to be a quarantine
and hospital tank. We haven't bought any new fish lately and
we don't really believe in treating sick fish with all the
patent medicines available, so the tank hasn't used for awhile.
I decided to set it up as a heating coil experiment and try to
refute or verify some of the conjecture that has been bantered
about recently.
(3) Some time ago, Karla was telling me about one of her
biochemistry procedures called "sodium dodecyl sulphate
Polyacrylamide Gel Electrophoresis" or SDS-PAGE for short. As
best as I could interpret, electrophoresis is used to determine
relative molecular weights of enzymes and proteins by putting
them on a plate covered with gel and applying an electric
field. After a time, compounds with different molecular weights
will have migrated different distances across the plate and
you can tell what they may be. Anyway, that conversation
planted the seed of "electric fields and organic things" in my
head somewhere.
(3) Recently, while going through piles of old fish magazines,
I came across an ad for a device that supposedly uses electric
fields or currents to denitrify water. Although my cynical
inner-self had me rolling on the floor in laughter, another
random thought was planted the murky backwaters of my brain.
OBLIGATORY SAFETY WARNING
Before I go further, I would like to state that what I am
describing could have the potential for danger. Keep in mind
that water and electricity are a deadly combination and should
not be trifled with. I am a qualified electrical engineer and
have taken appropriate precautions with the setup I'm going to
describe. I would strongly dissuade any one from trying to
dulpacate this until more information is discovered about the
processes involved.
HYPOTHESIS
The stated purpose of substrate heating coils is to create
slow convection currents that bring nutrients such as NH4++,
Fe++, Ca++, Mg++, etc. into the root zone for eventual
adsorption by the plant roots. Besides the water currents
that keep the substrate rich with nutrients, the coils add
heat to increase plant metabolism. Finally, the slow currents
allow nitrifying bacteria in the substrate to reduce oxygen
levels so that the trace elements don't oxidize. So far, in
my experience, the coils have been shown to provide the plants
with good conditions for long term growth, but they have NOT
been shown to affect the growth rate. Always the greedy one,
I am trying to find a technique to increase the growth rate
above the already rapid rate allowed by CO2 injection. And I
may have stumbled on to something.
SETUP
I have tried to set up the 29 gallon tank in such a way that I
can get some fairly controlled results. I have divided the
substrate into two halves (right and left) by glueing a 4"
tall piece of acrylic down the middle. The barrier will
divide the substrate into two halves but will allow everything
else in the tank to be shared. I am using two old AquaClear
200s for mechanical filtration and two powerheads centered in
each half at the top of the back glass for water movement. Two
Tetra CO2 bells are next to each powerhead and fed by a DIY
yeast CO2 generator. A 48" shoplight with a Triton and an
Ultra Tri-Lux bulb is centered over the tank, providing light
from the top as well as some from the ends. The substrate is
3" of 2-3mm quartz gravel (Tex-Blast) with Dupla laterite
mixed in the bottom third. With the addition of heating
coils, the setup is very close to an "Optimum Aquarium".
I have been following our typical maintenance regimen: 25%
water change every two weeks, addition of 1 Duplaplant tablet
at water changes, 2 Duplaplant-24 drops every day starting 3
days after a water change, replace evaporation losses with tap
water as needed. The water hardness is maintained at 4.5 dKH
and is 3 dGH. Enough CO2 is being injected to hold the pH at
just under 7.0, corresponding to about 15 ppm CO2.
The only significant difference is the way the heating coils
are setup in each half. The right half has 12' of 28 gauge
insulated wire, giving about 50 watts of heat with a 12v DC
power supply. The left half is the same, except I have used
BARE WIRE instead of insulated wire.
What I am trying to do is this: by creating an electric field
in the aquarium, I am trying to force the migration of cations
(positively charged ions like NH4+, Fe++, etc) down to the
substrate and negatively charged ions like (NO3-) to the top
of the tank. The bare wire has a linear drop from 12v to 0v
along its length; it is laid in a paired-serpentine pattern
such that the two ends are together giving an average 6v field
at that point and the average at all points along the length
is 6v. The DC supply is connected as a -12v supply, so the
substrate will have a negative charge with respect to ground.
I was using a "Solution Ground" (titanium probe) at the top
of the tank connected to a +6v supply to supply the other half
of the field giving a 12v potential from top to bottom. Since
the water potential is only 6v to ground, it should be
perfectly safe to work in. When I was planting plants, I
could not detect or feel any electricity at all.
To enhance the effect of the electric field, I am overdosing
the tank with a chelated iron compound. This should greatly
increase the conductivity of the water. I am shooting for an
iron level 100x as much as is normal (10 ppm versus 0.1 ppm).
After watching the fish in the tank for awhile, I decided the
probe was not the best idea. The fishes lateral lines are
very sensitive to electric fields and they were apparently
aligning themselves to the field: they were all leaning toward
the probe no matter what their orientation. A very strange
effect, indeed. To counter this, I ordered some titanium wire
from Edmund Scientific and ran a loop around the top of the
tank just below the water surface. This completely cured the
fishes tendency to lean.
BIOLOGICALS
The tank has been cycled and running for 6 weeks now. The
tank has 6 medium sized M. Bosemani rainbows, 12 otocinclus,
4 corys and 2 small farlowellas. The fish are fed 1/4 tsp of
TetraBits daily.
The two halves of the tank are planted identically and
symetrically. Each half has:
6 stems of Rotala macrandra
12 stems of R. rotundifolia
3 stems Bacopa caroliniana
2 small Anubias barteri
1 Echinodorus bleheri
4 E. quadricostatus
4 Cryptocoryne wenditii
1 Samolus parviflorus
There were also 10 Malaysian trumpet snails (about 1/2" long)
initially. Their population seems to be steadily increasing.
RESULTS
The results so far are nothing short of amazing.
Plant growth is distinctly different on each side of the tank.
On the right side (insulated coils or "normal"), the growth is
typical of our other CO2 injected tanks: the stems plants need
trimming about once per week and the rosette plants put on two
to three new leaves per week.
On the bare coil side or "special", the plant growth is more
than I hoped for. It is easily double what the right side
has, both in height as well as stem thickness and leaf size
and density. I cannot really justify this growth based on
availability of more nutrients; there must be some kind of
electro-bio-stimulation going on. It's as if the voltage
potential in the water is supplementing the available light
energy to dramatically increase photosynthesis. There are
far more O2 bubbles on the left side plants than the right
side.
If this were the only positive result, I would be more than
happy. However, as I observe the tank I have been noticing
more and more amazing effects.
In a well lit tank, most green plants will have some reddish
coloring on the leaves nearest the light. The plants in the
"normal" side exhibit this. However, the plants in the
"special" side have the exact opposite effect: the leaves and
stems near the bottom of the plant are reddish and the top
leaves are bright green! About the only reason I can think
of for this is the electric field: the Fe++ is being prevented
from getting to the top of the plant or perhaps even being
repelled by the positive charge at the top.
The Rotala macrandra, normally a plant with a mottled red-
orange-green appearance under good light, is exhibiting an
even stranger phenomenom. There are color gradations going
from bottom to top: red at the bottom, then orange, a tinge of
blue and green at the top. Much like the SDS-PAGE gel
procedure, the electrical potential seems to be holding
various trace elements at various levels in the plants. An
obvious application of this is to grow plants specifically for
color coordinated landscape scenes: blue plants for blue
gravel, etc.
I have also noted that the Malaysian snails do not seem to
live on the special side of the tank. I have never seen one
over there and have not noticed any in the gravel. I have
noted, however, many empty shells just over the acrylic
barrier. It's as if they tried to scale the wall and were
zapped when the reached the other side. An electric fence
for snails, as it were.
Fish health has also been affected in a positive way. When
we got the otocinclus, they appeared to infected with ick.
Since they were the only ones around, we decided to buy them
anyway. After being in the tank for a day, we noticed fewer
spots on them. Close observation showed us that the ick was
dropping off the fish and was actually being attracted to the
positively charged top wire. Unable to fulfill its normal
gravel-living growing phase, the infection was immediately
halted.
Water quality was also positively affected. We monitored the
nitrogen cycle from day one and noted that the cycle appeared
to complete in 1/3 the normal 5 to 6 weeks and the levels of
ammonia and nitrite were very low (< 0.2 ppm each). We have
also not been able to measure ANY nitrate. We do note a
constant low level bubbling at the positive top wire and
conjecture that the NO3- is being attracted to it and is being
electrolyzed into N2 and O2. This in itself is a significant
advancement in the aquarium State-of-the-Art.
The final noteworthy phenomenom is the affect on algae. Both
sides of the tank have had some minor green beard algae. The
otos have been keeping it under control on the normal side.
The special side seems to have given plants the ability to
repel the algae. If you look closely, you can see small
strands of algae growing in the plant leaves, but it is
standing straight up. Under careful observation, you can
actually see the algae begin to quiver, detach itself from the
plant and head straight for the top wire where it disappears
in a little cloud of bubbles!
I hesitate to report the final observation for fear of
ridicule, but I feel it is my duty to be as impartial as
possible. I have not yet confirmed the following, but an
analysis is in progress. I will give updates when the final
assay is in.
We had some blue-green algae (BGA, cyanobacteria) developing
in our discus tank. With all the positive benefits noted so
far, we decided to move the affected plants to the special
side of the 29 to see what would happen. At first, nothing
appeared to happen. We did notice the slime algae beginning
to loose it color right before the lights went out and figured
it was dying or dissolving.
The next day, it appeared that the BGA had disappeared but on
closer examination noted a discoloration of the plant leaves
where the algae had been. They appeared to be a yellowish
color. We removed the plant from the tank and brushed the
leaves where they were discolored. The yellow color came off
as a thin film with a metallic sheen. As silly as this
sounds, it appeared to be gold leaf. We took a few of the
samples down to the local assay office and are eagerly
awaiting the results. It looks like this hobby may finally
pay off!
George Booth, Ft. Collins, Colorado (booth at frii_com)
Back on-line! New URL! Slightly new look! Same good data!
http://www.frii.com/~booth/AquaticConcepts/