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Re: laterite in the Philippines
We just returned from Cebu/Mindanao this July; too bad I didn't know
you then because I would have visited you in Cebu City.
As for substrate, this will depend mostly upon two factors: which
plants you will want to grow and what chemicals you can get access to.
Can you get Seachem Flourish there? This is a relatively inexpensive
chelated iron fertilizer which also has other trace nutrients. I don't
know if this is over your budget or hard to find. Another alternative
is to get some chelated Fe trace element mix. This may be hard to find
in the Philippines but it is worth trying to locate it as this is the
cheapest way to get this kind of fertilizer. If you are really stuck,
I can send you some by mail.
It is also good to use an iron rich soil as many kinds of plants
especially Cryptocorynes, can get iron from the substrate. The problem
with soil and clay especially, is it can make a mess when you uproot
plants. If you get cloudy water, you may need to drain all your water
and replace it and that can be tricky with fish in there. Still, I
think the improvements with soil are worth it IF you are careful. It
is best to find an iron rich soil such as the red soil which you
should be able to find if you have a friend from Mindanao or if you
can find it on Cebu. I think it must also be there but where? Even if
the soil is light red or brown, it will have enough iron. Use a
natural soil, not something you get in the garden store. The garden
store soils are very, very fertile and that is not good in an
If I were you I'd put a 1" layer of soil/clay in the bottom of your
tank and then cover this with a 1" mixture of 50% by volume of peat
and sand. This is about 1:10 ratio by weight. Cover that with 1"
coarse sand or fine gravel of about 2-3 mm in size. Try to avoid beach
sand as it contains lots of coral and shells and is not ideal for
Crypts (too much calcium). Beach sand also may contain algaes even if
it is long dried.
For chemicals you need to find MgSO4 (Epsom salts), KSO4 (potassium
sulphate). Is it possible for you to obtain an analysis of your local water
from the water utility company there? This will tell you if you need to add
Mg or calcium (Ca). It is very probable that there is enough Mg and Ca
already in your water. The problem with water from the tap in Cebu is that
it may contain chlorine or even chlor-amine to inhibit bacteria. You can
remove chlorine by letting the water sit in a bucket or container for a day
or so but chlor-amine is harder. Do you have pH test kit? What is the pH of
your tap water? If it is 7.5 or higher, I think you don't need to worry
about Mg or Ca.
If you use peat and soil, and keep fish in your tank, you will probably get
enough nitrates from that alone. Peat does not seem to liberate very much
nitrates (at least what I have) and decays very slowly.
Potassium (K) is the element most like to be in short supply even from fish
food and soil and water. 1/8 tsp of potassium sulphate for each 10 gals of
water you drain out and replace will provide a steady supply. This works
out to around 10 ppm if I've done my math correctly and weighed the stuff
As for testing the clay, the best indicator is your eye. If it's red, it
has iron. Testing clay with water with your normal test kit won't work
because iron is not water soluble.
I think you should use the Australian peat (you only need a couple of
pounds) because the stuff from the forest doesn't sound like real peat to
me. It would reduce hardness certainly; anything organic will do that but
what you need is something which is acidic and has had most of the soluble
nutrients leached out of it. Otherwise, as it decays in the substrate, it
produces too much nutrients and you get blue-green slime, green water or a
filamentous algae explosion. The only way to tell if your peat is releasing
nitrates is probably to measure with a test kit. Maybe somebody else knows
Can you get a small container of bleach? You mix this 1 part with 19 parts
of water and use it to disinfect all plants which you put into your
aquarium to be sure they won't have any filamentous algaes. This is
especially important if you collect any plants from the wild. You dip the
plants in the bleach mixture 1-3 minutes and then rinse well with running
water. 1 minute for sensitive plants. 3 minutes for tough, thick leaved
plants if you have the dreaded Oedinum (sp?) green thread algae (feels like
What will you use for lighting for your tank? If you cannot afford the
electricity and the fluorescent tubes, a cheap alternative is window light.
You need an east or west facing window which gets sun for 2-3 hours each
day. This is very strong lighting but you can reduce it by adding curtains
or other shading.
What aquatic plants have you found so far?
What will you use for CO2?
Steve in Vancouver