Aquaponics Digest - Sun 03/22/98
Message 1: Re: Seaweed Extract addition for aquaponics systems
from "Ted Ground"
Message 2: Re: Aquarium Plants
from Gordon Watkins
Message 3: Small Systems
from "Sandy S. Brown"
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Subject: Re: Seaweed Extract addition for aquaponics systems
From: "Ted Ground"
Date: Sun, 22 Mar 1998 06:52:49 -0600
John,
As you may be aware, based on your comments regarding past work with
genetics, there are about 2300 enzyme systems coded in every cell of most
organisms (rule of thumb here, O.K.), so I would not be concerned about
"enzymes floating about in the fish tank or hydroponic beds", since the
biological world is already flooded with astronomical numbers and varieties
of enzymes- as you know, enzymes are what each gene produces or regulates
the production of.
I think the pat answer that some folks relay when answering why they add
seaweed is that the algae contains some levels of plant hormones or enzymes
that are not being provided in the soil or environment that the commerical
crop is being grown in. Based on Gordons' empirical experience and level
headed comments, it is clear that "enzymes" are only part of the
explaination as to why the crop benefits from the macroalgae, kelp, or
seaweed supplement. I am satisfied with the knowledge that a little bit of
seaweed seems to help the farmer safely produce a better crop, using a
natural, renewable resource such as kelp. I suspect that tomato splitting
is diminished from foliar spray because of mineral micronutrients being
delivered straight to the leaf and fruit, rather than any enzymes being
involved. For example, some minerals such as calcium translocate from the
roots to the end of the leaves much slower than they should during rapid
growth, the result of which is called "tip burn". The common fix for that
is to try to enhance evapotranspiration in the greenhouse by directing
inside circulation fans across the vegetation. This may be happening in
the case of tomato splitting- not enough mineral delivered to the fruit
fast enough during rapid growth. The foliar spray probably gets that
mineral there faster than the vascular system is delivering it. I am just
speculating here, so, who knows?
It is possible to over dose the crop with seaweed. For example, my young
son was sent down to the garden last spring to foliar spray the bell pepper
plants. We thought we had the dilution procedure well established, but
apparently he inadvertantly "nuked" the plants with a high concentration.
Just the chloride level alone may have harmed the plants, but we noticed
abnormal leaf morphology and "lanky" stem growth for a few weeks afterward,
so there is indeed some basis to the claim that cytokinins, or similar
substances, are present in seaweed, but again, that is not the "whole
story".
Ted Ground
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Subject: Re: Aquarium Plants
From: Gordon Watkins
Date: Sun, 22 Mar 1998 17:26:06 -0600
Yes, Wendy, my angelfish actually ate the hygrophila leaves, but not the
stems. Interestingly, they don't bother the established hygrophila from
which I took the original cuttings for propagation but they go nuts for
the emersed hygro when it's reintroduced. Perhaps the leaves from
emersed plants are more tender?
The reason I'm interested in emersed production is mainly because of
the space constraints of growing plants in aquaria, as well as lighting
requirements. I have lots of aquaponic bed space (compared to aquarium
space) which is naturally lit in a greenhouse so the potential for
growing commercial quantities is much greater. I've had much better luck
propagating hygro in my beds than in aquaria, probably because the
lighting in most of my tanks is less than optimal, but re-acclimating
the plants to submersed conditions is a little tricky, at least with
angels around.
Gordon
Wendy Nagurny wrote:
> > Did your angelfish actually EAT all of it, or did they just shred it up? I
> thought that freshwater angels usually only picked at greens (but they DO
> enjoy their toys).
>
> > Except for propagation from seed (ie your crypts), why would you want to
> grow these plants emersed? Hygrophila propagates easily from submersed
> cuttings, as do many other aquarium plants. Or is this just for the fun of
> it. Then you don't need a reason. :-)
>
> ----------
> >
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Subject: Small Systems
From: "Sandy S. Brown"
Date: Sun, 22 Mar 1998 23:44:10 -0500
Patty,
My husband, Ralph, and I have recently set up a low budget, small-scale
system, and our logistics might be helpful to you. We have it located in
an uninsulated (it should have been insulated, but it hasn't happened yet)
8X8 ft. greenhouse, that used to be part of our backyard woodshed. The
north wall and east wall (abutting the remaining woodshed) are made of tin
scrounged from an old roof, with silicone caulk used to seal holes and
tears. The lower part of the south wall is wooden (simply to keep the snow
from blowing in when the section was woodshed). The upper portion of the
south wall, the roof, and the southern and western walls of the "west wing"
(8X11 ft.) are composed of corrugated Fiberglas panels screwed to joists on
24" centers, with the edges and screw holes sealed with silicone caulk.
The tank is a 65-gallon kidney-shaped plastic preformed pond, purchased
from our local home and garden chain, set into the ground. A filter, made
from a 20-oz. soft drink bottle, with the bottom cut off, holes all the way
around the bottom edge (these give extra space for the water to be pulled
in) punched with a paper punch, and a circle of nylon window screen (made
three times as large as the bottom of the bottle, so that it puffs out, and
provides more surface area) held in place with a wide rubber band, is set
horizontally at about mid-depth in the pond to prevent small fish and large
debris from being sucked through the pump; having it held rigidly in place
saved our yellow perch, when a chunk of ice plugged the return pipe, and
half of the water was pumped around the ice, and out of the system. The
filter slips directly onto the end of a piece of 1/2" PVC pipe, and is
replaced with a clean filter when the screen fouls with algae; the nylon
screen is very easy to clean for next time, bends more easily than metal
screen would, and there is no potential danger from galvanizing as with a
metal screen. Water is pumped from the pond through the filter and PVC via
a 12 volt motorhome water supply pump (check the mail-order auto parts
suppliers). These pumps are not designed for continuous use, but we have
used one for four months before replacing it to remove the algae from the
inside. Plumbing, up to where the plants are located, consists of flexible
tubing, wrapped with white electrical tape to decrease algal growth, and
1/2" PVC. Part of the water (the majority) goes through PVC directly back
to the pond, with a valve to control the volume of flow, and the outlet
several inches above the water surface to provide oxygenation. The
remainder of the water is pumped to near the ceiling, where it runs through
an X-connector to short pieces of PVC with holes drilled in them, so that
the water dribbles into a two-gallon plastic paint bucket under the lid.
The bucket is filled with plastic hair curlers, that serve both to de-gas
the water, and as a substrate on which Nitrobacter and Nitrosomonas
bacteria grow. [Note that we probably would have been much better off
running all of the water through the bucket, and then splitting it
off--live and improve.] A bulkhead fitting in the bottom of the bucket
allows the water to progress by gravity flow. The water then goes through
PVC to a T-connector. One piece of PVC, capped on the far end, comes off
each side. Two holes are drilled in the bottom of each piece of PVC and,
held in place with silicone caulk in each hole, is a six-inch piece of 1/4"
black electrical shrink tubing.
The lower end of the shrink tubing is threaded into a hole in the top of a
piece of 2" PVC. 1 1/8" holes (use a hole saw) in the top of each piece of
PVC, on 7" centers (that worked out best for the length of our run), go the
length of each pipe; these are where the plants will be located. The pipes
are on 6 1/4" spacing, supported along their length by three pieces of 2X4,
hole-sawed to create depressions for the pipes, with the spacing
arbitrarily chosen because it allowed a comfortable reach for me to the
back pipe, and reasonable growth space for the plants. Holes are slightly
offset on adjacent pipes to allow more room for the plants. The upper end
(near the shrink tubing) of each pipe is capped. The lower end of each
pipe (just low enough to allow continuous water flow) is open, but a hole
drilled through the top and bottom of each pipe, 1/4" back from the end,
allows a piece of wire to be threaded down into the trough (22" long piece
of PVC, cut in half lengthwise and capped) so that the water will continue
to flow into the trough if something causes a drop in the flow rate,
instead of the water drooling back along the bottom of the pipe, and onto
the floor. A fitting in the center of the trough directs the water back
from the plants to the pond via 1/2" PVC, again allowing a splash effect as
the water returns to the pond. Valves are placed in several places along
the plumbing prior to the plant pipes--when in doubt, put in a valve; you
may not need it, but they're not that expensive, and it's a whole lot
easier to put them in in the first place, rather than trying to splice them
in later.
Our only heat at this time consists of a 120 volt water heater element in
the pond, hooked to a timer, set to come on for two one-hour periods during
the night, and turned on manually at other times, if the weather warrants
it. A 12 volt automotive fan, with wooden ceiling fan paddles attached to
two of the four vanes, spins slowly on the ceiling, to keep the air moving
and the frost from settling on the plants. The pump and the fan are
operated off of a pair of 6 volt, 220 amp-hour golf cart batteries,
connected in series. At this time, we use a 120 volt battery charger to
top off the batteries but, as soon as possible, we'll draw power for them
from the sun or wind.
I soak the seeds for 12 to 24 hours, then pop them into 1" Oasis Horticubes
(try nursery supply places). The cubes either go directly into the
aquaponics system then, or they go into plastic trays from cordial cherries
(perfect fit!) in the living room window, being watered daily with water
from the indoor fish tank. Larger transplants can go directly into the
holes in the PVC, without cubes or any other assistance. Since our fish
density is not very great at this time, I also drip on each plant a bit of
a 1:64 dilution of Sea-Plus ("liquid fish and seaweed") 3-2-2 fertilizer
about once a week.
Best wishes,
Sandy Brown
>I would like to subscribe to the mailing list. My daughter and I are
>interested in building a (very) small aquaponics system using tilapia (prob. a
>30 gal tank) and herbs. I am looking forward to this wonderful learning
>experience for both of us.
>
>Sincerely,
>Patricia M. Ragen
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