How to Grow Beautiful Aquarium Plants (cheap)!
or How to Build a
Aquatic plants receive carbon dioxide (CO2), potassium (K),
magnesium (Mg) and calcium (Ca) primarily from the water. They can also
receive nitrogen (N), phosphorus (P), sulpher (S) and several other trace
nutrients (Fe, Bo, Mn, Cu, Zn, Mo) from water however these can also be
absorbed by roots in the substrate.
Retaining phosphate and iron sources in the substrate helps to limit
availability of these nutrients to algae. This is the secret to growing
beautiful plants without serious algae problems! In fact, most aquatic
plants grow much,
much better when they get nutrients from the substrate.
In order for iron to be available from a substrate, you need to use
a clay, soil or iron containing substrate additive together with a small
amount of organic material such as peat. The organic material provides
nutrients for anaerobic bacteria to reduce insoluble iron (ferric) to soluble
iron (ferrous). It also releases humic acids which are natural chelator
chemicals which lock onto positively charged chemical ions like Fe++ and
make it available in the water. These humic acids also help to buffer the
pH in your aquarium to a good value. The downside is that humic acids interfere
with many test kits which measure CO2 and carbonate hardness.
This method shows you how to achieve adequate CO2 and carbonate
hardness without relying on test kits.
Here is a substrate design which is highly effective for me.
Put a large plate or flat plastic on the bottom weighted by a rock and
slowly fill the tank with water allowing the water flow to gently flow
onto the plate. If you disturb the water during filling, you will get a
lot of cloudiness. If you do, siphon the water out and refill again more
Bottom layer, iron rich clay, Micronized Iron or subsoil. This may
be mixed with sand. (New) About
2% Micronized Iron by weight is probably plenty. Iron fertilizers containing
iron sulphate such as Ironite are not suitable. Pottery clay is a bit difficult
to mix with other materials unless its in powder form so chop it into bits
and soak it in water for a week stirring often until its nice and soupy.
I like subsoil, it's easy, probably as good as anything and cheap. I sometimes
add a little F-T-E, fritted trace elements; (New)
about 10 small granules for each square foot of tank bottom (2" depth)
are about right according to the suggested usage on the package. Be careful
because it's easy to use too much. 10 small granules of F-T-E weighs about
0.12 grams (120 milligrams). That's about 1/70 of a teaspoon!
Middle layer, (New) 1
inch depth of mixture of garden soil mixed 4 parts to 1 part of fluffy
sphagnum peat moss by volume. Since garden soil is about 20 times heavier
than peat moss, this is a ratio of 1.25% by weight. This should be one
inch deep NO DEEPER!! (see notes). Mix a handful of Micronized
Iron with this if you have it to ensure that the soil has sufficient iron.
Iron is present in most soils especially if the soil in your garden is
good for growing plants. You can also mix the soil with sand if it seems
to be too rich. (see notes)
Top layer, 1 inch depth regular 2-3 millimeter aquarium gravel.
Plant your plants after the water level is a few inches deep. Plant
densely. Use fast growing plants initially. I suggest between 2 to 3 watts
per gallon of tank capacity of either fluorescent or metal halide lighting.
Good lighting and plenty of plants are important to the success of an soil
Change 25% of your tank water frequently on initial set-up. Initially
the peat will release a lot of humic acid and this will color the water
yellow. Activated carbon filtration will also reduce the yellow color and
help to remove excess iron from the water. At each water change, dose with
fertilizer according to the volume of water you drain off and replace.
Later as the peat releases less humic acids, you can reduce the frequency
of water changes. Water change frequency can be much less often then; I
think there's enough nutrients to last several weeks especially if you
add some NPK fertilized clay balls once or twice a year.
Nitrate and phosphate test kits are handy but not essential. If you
have used a rich organic material or a rich soil then you may need to be
concerned about high levels of nitrate, phosphate or ammonia initially.
Watch the ammonia concentration closely for the first month because ammonia
tends to be released from rich substrates. Over time a over-rich aquarium
substrate will become manageable especially if you remove the excess algae
and growth from fast growing plants.
A high quality iron test kit may also be useful. The peat and iron substrate
can release enough iron to cause minor problems with algae for the first
few months. That's why regular water changes are a good idea.
For fertilizer heat 3 cups of water to boiling in a large jar or measuring
cup. Add the following and stir until dissolved:
Put this into a 750ml bottle and keep in a cool place. Sometimes crystals
may form if its in the fridge so I add a half tsp of muriatic acid and
store it on my shelf.
1/4 cup of potassium sulphate
1/4 cup of epsom salt (magnesium sulphate)
1/8 cup of potassium nitrate (salt peter)
HINT: mix the calcium carbonate with a jar of water and add this at night
around lights off time. It will stay cloudy for several hours. A light
layer will also be deposited on the plant leaves but this dissolves slowly
by the action of dissolved CO2 in your water.
Add 1 tsp of this for each 5 gallons of aquarium water on startup.
Each time you change water, add 1 tsp of this for each 5 gallons of water
On startup, add 2 tsps of calcium carbonate for each 10 gallons of aquarium
water. SKIP this if your tap water is over 4 GH general hardness.
Each time your change water, add 1 tsp of calcium carbonate for each 10
gallons of aquarium water you replace. SKIP this if your tap water is over
4 GH general hardness. See notes on GH.
Note that the fertilizer contains no trace nutrient additions.
These are provided primarily by your soil.
(New) CO2 injection
VERY important for the success of a high light tank. I prefer
stronger lighting and CO2 because I want the plants really actively
growing in order to maintain the dynamic balance between nutrients, light
Use CO2 injection, either yeast method or compressed tank
with regulator and micro-flow metering valve. I'm not going to repeat the
excellent information already available elsewhere on the world wide web
about CO2 and lighting. See the Krib for more information on
CO2. Try to get 1 bubble per 4-6 seconds. I like to inject CO2
using a powerhead. See the pictures of powerhead CO2 injection
in the Hallway of Pictures. I like a sponge filter on the powerhead inlet
and no other filters to disrupt the water surface. For small tanks of size
27 gallons or less, I'd aim for 1 bubble every 8 seconds. For larger tanks,
4-6 seconds per bubble is adequate. The powerhead helps to introduce current
into your water which exercises the fish and greatly improves the rate
of CO2 transfer to the plants.
(New) Sufficient lighting is
important for the success of a high growth tank. I'm not going to repeat
the excellent information already available elsewhere on the world wide
web about CO2 and lighting. See the Krib for more information
on lighting. The examples of aquariums on my web pages typically are more
strongly lit than is necessary or optimal for algae management. I use the
MH systems because of their convenience and because I don't have to build
or buy a hood. If cost of operation is a concern and you want to keep the
extra heat to a minimum, I suggest you use efficient T8 lights such as
GE-SPX-50 together with electronic ballasts designed specifically for these
lamps. For a typical 18" deep aquarium, the watt per gallon rule is a good
indication. For Crypts and Swords, you should use about 1.5 watts/gal.
For faster growing plants, you should use about 3 watts/gal. More light
does not translate into more growth especially if the available nutrients
are limited. Often a dose of calcium, or potassium in the water, CO2
injection, or a few clay fertilizer balls is all you need to induce a tremendous
boost of growth even with your existing lighting (assuming that you've
met the watt/gallon guidelines) Please visit the Krib for TONS
of information about lighting!
Remember, strong lighting is not essential for growing Crypts and beyond
a certain point, does nothing to increase growth rates. Spectrum
and intensity may affect the coloration of some kinds of Crypts.
Crypts also have a tendency to melt in very strong lighting however I have
found that regular additions of calcium seem to help Crypts to
resist melting! This may be especially true if peat or leaves
rich in humic acid are used in the substrate.
Enriching the Substrate
(New) To enrich the substrate
fertility for heavy feeders like sword plants or large crypts, prepare
1/2 inch clay balls with about 10 granules of 14-14-14 fertilizer. Dry
these until hard and place 1 or 2 into the substrate near the roots of
heavy feeders. Repeat as necessary if growth rates become low (about 6
months). It takes about 1/2 a teaspoon of clay to make a 10 mm (1/2") ball
of clay. Each ball of clay will have about 70 mg of nitrogen which is the
equivalent of 300 mg of nitrate and about 70 mg of phosphoric acid (P2O5).
(Estimates based on 113 granules per teaspoon, a teaspoon weighs about
(New) GH or general hardness
is a measure of the amount of calcium and magnesium found in natural water.
I use this measure because there are test kits available which give readings
in GH. One degree of GH is the equivalent of 17.9 mg/L of CaCO3.
Thus if you have close to 70 mg/L or 70 ppm of CaCO3 in
your tap water, you won't need to add any calcium. Expressed as calcium
concentration (what really matters) this is equivalent to about 30 mg/L
Ca. One level teaspoon (5 ml) of calcium carbonate weighs 4 grams.
1 tsp for 50 litres of water gives you 80 mg/L. Other sources suggest that
1 tsp of CaCO3 / 50 L should give about 40 mg/L so it may be that the sample
I weighed is heavier because it has absorbed water from the air. Check
back at a later date for more info.
Sources for chemicals:
Bigger gardening centers carry many of the chemicals and things like Micronized
Iron and F-T-E fritted trace elements.
Drug stores carry epsom salts and can order many kinds of chemicals for
Pottery supply outlets carry large bags of calcium carbonate
See your yellow pages for chemicals
Hydroponics supply stores carry all the fertilizer chemicals
See the PMDD section
of the Krib
for F-T-E and Micronized Iron
The use of Micronized Iron together with peat should be considered experimental
as the iron is concentrated and in a highly available form. My experience
over a 4 month period indicates that humic chelated iron is being released
from the substrate but not at a level to create serious algae problems.
The plants which I grow (Cryptocorynes, Hygrophila polysperma, Bacopa,
Rotala, Aponogeton crispus, Saggitaria, Echinodorus, Heteranthera zosterifolia)
do not show indications of iron toxicity. I suggest using ordinary soil
first without Micronized Iron. If you use Micronized Iron, use it sparingly.
I take precautions to ensure that filamentous algae are not introduced
into my aquariums. See the Krib bleach information at: http://www.thekrib.com/Plants/Algae/bleach.html
Organic material and fertile soil is only used in a thin layer (1") close
to the surface because a deeper layer will receive less oxygen diffusing
from the surface and will become too low in reduction (redox) potential
thus creating toxins by the action of anaerobic bacteria. A one inch layer
is sufficient to provide enough reduction potential to ensure a long-term
supply of reduced and soluble iron. Refer to the technical article
on substrate materials for further discussion of redox potential.
Soil and/or peat substrates have been in use by many folks for extended
periods since the beginning of aquatic plant keeping so I consider them
proven. I've been successfully using a variety of soil substrates
for 3 years. Paul Krombholz has been using soil and peat preparations for
several years. This article is intended as a detailed procedure on how
to safely setup a productive soil tank. Although we know people have been
using soils of all kinds, we don't have good information on how to repeat
the successes. Bear in mind that soils do vary in composition somewhat.
It is always a good plan to keep careful notes and measure the quantities
of materials you use for later reference. Notes on regular measurements
of ammonia, nitrates, phosphates and iron concentration will also be very
informative. If you keep logs like this I would appreciate the information
if you are willing to share it.
When is a soil too rich? I do not recommend you use any compost
or soil treated recently with manure or other fertilizer within the last
year. (New) The
bagged soils which you purchase at garden centres are NOT
suitable; they are too high in nutrients and organic material.
The best dirt for your first try is stuff you dig up out of the ground
from a well drained location where there's been grass growing for years.
It will be well leached of soluble nutrients. If you really want large
crypts and growth, you can use more fertile mixtures but you may have to
deal with algae problems. Ammonia is also released from very fertile substrates
for about a month after submergence.
(New) If you feel that the local
soil is simply not suitable and you decide to use a packaged soil despite
the high fertility, then you should mix this with a larger volume of sand.
Note that the fertilizer contains no trace nutrient additions.
These are provided primarily by your soil. Sometimes a local soil may entirely
lack a mineral like manganese, copper, molybdenum, boron or zinc but these
soils are very rare. Your local gardening experts will be able to tell
you if the local soil needs a trace nutrient supplement. In these cases
a small amount of Fritted Trace Elements (a tsp) well mixed into the bottom
layer should be safe and sufficient. Less is better than more.
If you have hard water and are not adding the initial dose of calcium carbonate,
practice regular water changes to ensure enough calcium. Peat soaks up
calcium. Regular water changes also helps to prevent a build-up of humic
acids and humic chelated iron in your water which may occur in the first
If you know your tap water contains over 10 ppm of magnesium, you can skip
the epsom salts in the fertilizer. The same is true for nitrate (+10ppm)
and potassium (+10ppm). Calcium levels over 50ppm (as Ca) should be sufficient.
Some soils also contain calcium carbonate or calcium sulphate as well as
magnesium. These are limestone soils and are quite alkaline. You can test
a sample in water for pH or using the acid test for fizzing. Your gardening
center experts can also advise you on this condition. With peat, such soils
should not be a problem since the humic acidity of the peat will provide
a stable pH and help to absorb excesses of soluble calcium and magnesium.
Such soils are more prone to lack iron.
Initially, for the first two months, some soils will release a significant
amount of nutrients such as nitrates, ammonia, phosphates and iron. Nutrient
release is highest at 4 weeks and declines rapidly until it is nearly stable
after 10 weeks. This can cause a few problems with algae such as green
spot algae on plant leaves. Some of these problems can be avoided by keeping
the soil sample in a 5 gal bucket with water for a few weeks to release
the majority of nitrogen and phosphorus nutrients. Drain the soil well
before mixing it with the peat and Micronized Iron . The peat can also
be treated by the same method to reduce the levels of humic acids released
during the transitional period. When using such wet mixtures, you should
probably fill the tank with water and drain it once before refilling and
planting since the wet soil and peat will contain nutrients which would
be released quickly. Weigh the peat when its dry since it is the dry weight
ratios which are important.
(New) The mineral nutrient method
described above can still be used if the substrate does not contain iron
and organic material. In this case, 1 tsp of chelated trace element mix
should be added to the mixture (3 cups of water). This is amount will produce
approximately 0.1 ppm of chelated iron when dosed as directed. It may be
necessary to prepare a separate solution of chelated trace nutrients (mainly
iron) which are added more frequently according to the PMDD methodology.
The mineral nutrients do not need to be dosed frequently since these nutrients
are not lost over time. Chelated iron is lost from solution by the break
down of the chelating compound however EDTA and DTPA are the most stable
chelating compounds. For a more information on chelated trace nutrients
and sources see the PMDD section of the Krib at http://www.thekrib.com/Plants/Fertilizer/.
Refer to my detailed substrate article
for more information on soils, precautions and other substrate materials.
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