Plants in an aquarium serve several functions:
- they look good
- they provide a hiding space for nervous fish and babies
- a heavy concentration of plants will consume much of the nitrate
produced by bacteria acting on fish waste, thus reducing the need for
water changes
There are two schools of thought on succeeding with a planted aquarium:
low-tech and high-tech.
Low-Tech
The low-tech planted aquarium is based on the idea that plants grow in
dirt. The theory is that if you place garden or potting soil at the
bottom of the tank, with a thin layer of gravel on top, this plus fish
waste will supply the nutrients that the plants need. Supposedly you
then won't need all of the plant nutrition supplements sold at aquarium
stores because these are only required when the aquarium environment is
sterile. A chief exponent of this point of view is Diana Walstad,
author of Ecology
of the Planted Aquarium, which is well worth reading even if
you ultimately decide to go the high-tech route.
My personal experience with a low-tech aquarium started off dismal. I
put a thick layer of supermarket potting soil underneath the gravel in a
90-gallon tank with 160 watts of light (4 48" fluorescent tubes) . It
turned the water brown and yet supplied so little iron to the water that
I could not get a reading from an iron test kit. The first batch of
plants started to die within two days, with the leaves turning yellow
from the tips downward. I consulted a couple of experts and they
postulated that the plants were being overfertilized with phosphates
from the soil. Their theory was that the deaths were too rapid to be
from iron deficiency. Another worrisome factor was that the water in
the tank is extremely soft. Boston tapwater contains no minerals. This
may lead to CO2 deficiency because of the lack of carbonate hardness.
Also, the tanks was being over-agitated by a couple of low-quality
Tetratec Pro filters (see the filtration
section for a discussion of why these are so terrible). Surface
turbulence tends to allow CO2 to escape from the water.
With little to lose, I changed 80 percent of the water in an attempt to
get rid of excess phosphates. The tank become quite clear. Then I
dumped in double doses of plant mineral supplements. The plants began
to recover a bit.
I left the tank on its own for two months. The water turned brown
again. Brown-green algae proliferated. Many of the plants survived but
none appeared to flourish. Maybe it was the algae but something botanic
was using up the nitrate produced by the filter bacteria; nitrate levels
were 0 despite the lack of a water change during those two months. I
did a 90-percent water change and replaced the noisy ineffective
Tetratec filters with a Rainbow-Lifegard system including UV sterilizer.
High-Tech
The high-tech planted aquarium was pioneered by Europeans and is
sometimes referred to as a "Dutch Aquarium". You rely on nature for
nothing. You use a purpose-made substrate. You fertilize that
substrate periodically. You inject CO2 into the tank. Here is the
formula that works for Phyllis, the woman behind www.trueaquariumplants.com,
for a planted Discus tank:
- Seachem Flourite substrate, 2.5-3" deep, thoroughly washed (this
stuff makes the water incredibly turbid; you'll have to do a couple of
100 percent water changes after you put it in; the turbidity is bad for
the plants and clogs their pores)
- Seachem Flourish fertilizer tablets every three months (but not for
the first two months; the Flourite substrate is already treated with
fertilizer)
- Eheim canister filter
- a powerhead close to the bottom of the tank generating a current in
the water but not on the surface -- this is so that plants develop
strong anchor roots
- CO2 injection, from a Carbo Plus if your tapwater has a high general
hardness, from an Eheim bottle-based CO2 system if tapwater is soft
(lower than 8 degrees of German Hardness)
- Seachem Discus Buffer to lower the pH (the CO2 injection also lowers
the pH)
Plants in a high-tech aquarium grow much faster than plants in even the
most successful low-tech aquarium. What has never appealed to me about
the high-tech approach is the CO2 injection. If it goes awry there is a
danger of killing the fish. If you are using a bottle-based system, you
have to obtain a new bottle from a gas supplier every 3-6 months.
Lighting
Whether you take the high-tech or low-tech route, remember that you'll
want fairly strong lighting (1.5-2 watts per gallon is considered the
minimum). The easiest way to get to this level is by purchasing the
aquarium manufacturer's glass hood for your tank. Then toss as many
compact fluorescent strip lights on top as will fit. Avoid standard
fluorescent strip lights. They work great for a year and then the
ballast begins to make an annoying mechanical buzz. Compact
fluorescents have silent electronic ballasts.
Note that placing the tank near a window where it can catch sunlight
also works.
Books
If you want some inspiration, pick up the beautifully photographed books
by Takashi Amano:
philg@mit.edu
Related Links
- Fish Forum- An online community for fish and aquarium
experts, enthusiasts, and hobbyists of all ages. (contributed by Fish Forum)
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