The Learning and Application Tango
by Bart van Dijk
From the Newsletter of the Vancouver Aquatic Hobbyist Club, February 2001
Aquarticles
Ever since I hooked a seventy pound spring salmon in the Birkenhead River, I was
determined to some day "grow" a whole lot of them by running my own fish farm.
So when fifteen years ago I was told that my job would end in a year, the natural thing to
do seemed to be to use that year to make a complete switch of occupation. In connection
with this I decided to first get to know the ins and outs of treating fish farm waste
water in a hydroponics type set up. Growing exotic vegetables, preferably ready to eat
totally out of season, would be a very profitable sideline.
...I bought twenty five feet of 2" flexible hose, strapped it in horizontal loops
onto a forward sloping table, and cut about a hundred holes in the tops of the hose. I
suspended an eight unit light fixture over the table and filled an eighty litre garbage
pail with hydroponics solution. My Whisper Air Pump could just manage to pump this to the
top of the 2" tube, and then gravity caused it to flow through the hose, soaking all
the plant roots back to the garbage pail. An extremely cheap way to do it - yes. But as it
turned out, too cheap.
When using a hydroponics solution for a short time there are very few problems, and as
soon as problems show, you make a new solution. Re-using the solution, and thus having to
add the chemicals used up by the plants, is the challenge. Hydroponics growers are guided
by lots and lots of charts showing symptoms and their probable causes. For instance,
Western Water Farms' description of calcium deficiency symptoms: "Chlorosis generally
begins at tips and margins of young leaves, progressing between veins, followed by
necrosis; terminal buds die and turn brown or black in colour; roots characteristically
short, bulbous, with necrotic apical meristems." Pretty straightforward you say? But
have a look at symptoms of iron deficiency: "Intervenal chloroses of young leaves,
veins remain green; entire leaf including veins becomes yellow or white in colour."
And then this one for iron toxicity: "Intervenal chloroses of young leaves, veins
remain green, later leaf becomes yellow or whitish." There are similar descriptions
for a total of twelve shortages and twelve toxicities.
My plants grew well for a while - everything was hunky-dory apart from a constant pH
problem requiring adjusting each morning and each night, and the orchids going dormant.
Finally the symptoms I was itching to learn how to correct started to show up, but
absolutely nothing made any sense at all. Well, after about two months I tracked
everything down to poisoning by the emulsifiers used in the plastic manufacturing
process. These were slowly leaching out of the new plastics. All that time was not a
complete loss, for during that period I learned how to control the pH by careful
adjustment of the iron content of the solution. The orchid shut down turned out to be due
to lack of infra-red light to trigger those plants. So two steps forward and one
backwards. Lesson learned for ever and ever!
...Two years ago my 100 gallon wooden tank sprung a leak. My koi needed a bigger place
to swim in anyway, so I bought a rectangular blow-up plastic kiddies' pool and put in my
seven koi. The first day went fine. The next day the fish were uncomfortable so I changed
about a third of the water. The third day trouble straight away, so I changed as much
water as my hot water tank could supply. The fourth day two fish were upside down, so I
set the water running in and out, and "walked" the fish by hand for what seemed
for ever, but they died. I went out and bought a big glass tank and straight away the
remaining five fish started to feel better. (Kiddies' pool $60, aquarium $300!).
...Last winter I read about raising little fish in quart sized dishes floating in a
basin. This has many advantages: you can clean the dish really easily (using a turkey
baster), the replacement water is at the right temperature, and you can add new water to
the basin and be ready for the next water change. So I found a terrific deal - a solid
plastic basement type washbasin $13, legs included. But after the third water change, the
little fish gave up the ghost en masse.
Isn't it amazing how blasé we tend to become after a period of no trouble ? We know
the theory, but do we take action? - not until it hits us. What action to take with new
plastic? I don't know, but it has been suggested that "pickling" it with salt
helps.
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