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Re: trimming and richer substrate
Please allow me to clarify a couple of points. Earlier I wrote:
> A better substrate would be one containing clay and or an amount of soil
> mixed with sand in a lower layer. If you are using soil or other organic
> additives, my opinion is that there is not much point in using laterite.
> If you're going to use the real laterite, your strategy is going to be
> to avoid sources of organic acids (like some soil types) because you want
> to use an automatic pH controller to precisely control CO2 injection.
What I'm trying to say here is that I think there is not much point in
mixing an expensive laterite with other materials for a substrate. There
are other sources of iron oxides such as micronized iron and soils which
are cheaper and easier to find. The big point about laterite is the things
it doesn't have in it which you MAY not want. This means relatively low
amounts of organic material (it gets in there eventually from the fish),
organic acids and nutrients. Real laterite is also relatively low in
silicates but it's doubtful that this is important. Stick to one strategy
and don't go mixing things together wildly thinking more is better. These
strategies are quite different and you need to understand nutrient
requirements before experimenting too much.
The reason why the choice of substrate is affected by your algae prevention
strategy is that organic substrates tend to release very large amounts of
nutrients such as nitrates (and phosphates) into the water for the first
few months. You need to regulate the amount of chelated Fe you use quite
closely and try to provide an environment without contamination by
filamentous algaes. That implies bleaching the tank and plants prior to
installation or getting them from a known sterile tank or taking emersed
cuttings. Perhaps my experiences with a rich substrate are exacerbated by
my strong lighting. I suspect that it may be easier to maintain a soil or
peat tank under low or moderate lighting conditions.
My first experiment with a rich substrate mix using earthworm castings,
clay, gravel and osmocote is a disappointment. While I was away, the tank
became overgrown with a fur algae probably from some delicate plants I
introduced without bleaching. I also experienced early problems with green
water and cyanobacteria which made the early stages of the tank a
maintenance hassle. Growth was very fast and I have some huge Crypts from
this tank. I suspect I will have to bleach them and restart the tank with a
relatively infertile substrate. I may try adding several SAEs to this tank
to see what happens.
My latest substrate experiment is going much better. The tank does have
contamination with brush algae however it does not seem to be a severe
problem. No problems with green water or cyanobacteria. This is a deep
substrate. I used small amounts of micronized iron and fritted trace
elements in the bottom layer mixed with a lot of sand. I was concerned
about iron and trace element toxicity so that's why its relatively deep.
The middle layers have more organic material. It also has a commercial
product called basin soil which has sand, peat and other materials. This is
all described in a previous posting on the APD earlier this year. There is
quite a bit more sand in this substrate since I didn't want high nutrient
levels and I wanted to reduce the rate of diffusion of nutrients coming
from the substrate. In contrast, low fertile substrates work by allowing
nutrients (ie fish poop) to work INTO the gravel. With organic substrates
you prefer that decomposition and release of nutrients is very slow and
that diffusion of nutrients out of the substrate are also slow.
Growth in this tank is not as rapid as the other tank but the health of the
plants is very good. This tank is still producing bubbles from the
substrate after several months but it doesn't appear to be a problem. It
now looks like a very nice tank; I better photograph and video it quick
before something disastrous happens!! I've also greatly reduced the density
and number of species plantings in this tank and opted for several
specialty plants like E horemanii, E barthii, and a very large and very
small crypt which could be C blassii and C nurii but I forget which is
which and could find no reference to identify them with in any of the
Baench atlases. Is there a better reference for Crypts?
Another reason for making this substrate deep is that I'm hoping to make
the substrate self-sufficient for Fe. The plants don't seem to be suffering
from lack of Fe but the H stricta still shows some signs of Fe deficit and
slow growth. Pennywort also shows Fe deficit and floating plants grow very
slowly. It looks like many plants like Crypts can tolerate low Fe levels
and get their requirements from the substrate but other rooted types
cannot. Maybe it takes a long time for things to reach a satisfactory
Ok enough rambling. Bye...
Steve P in Van.