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Re: Aquatic Plants Digest V3 #595

> From: George Booth <booth at frii_com>
> Subject: Re: Muddy Thoughts
> Why don't you stop changing the "Subject:"? That way people who want to
> follow
> along would have an easier time.

Ok, I'll leave the subject as it is this time. ;-) hee hee

> Let me address your last comment first since I have evidence that you don't
> read
> all that is posted before replying.
> >George, you come out with this wild theory that laterite is fertile
> >because heating cables draw nutrients into the substrate and you have
> >NO EVIDENCE to substantiate this claim.
> Bummer, you forgot to read the last part of my post.
> I have EVIDENCE that gravel+laterite+heatingcoils produces great growth. The
> evidence is in the three aquariums I maintain.

I knew you'd say that. That reasoning is post hoc fallacy. Let me offer
a different explanation.

I think you do have good growth in your tanks. I'll stipulate to that. I
think you are getting iron minerals from the laterite (in addition to
the chelated iron) and this is helping the plants. I doubt that the
laterite is giving the plants much nitrogen or phosphorus but you have
the Dupla substrate tablets which boost phosphates during the initial
setup. With a lot of plants, you're going to have quite adequate growth
using the Dupla method, the Randall method, the Booth method or the PMDD
method. Getting adequate growth is not what the original subject was
about. It was about mud and the fact that it was a "richer" source of
several nutrients than sand or laterite mixed with tiny gravel pebbles.
(geez, I s'pose you could call it sand; some folks in the building trade
do as do the sand, er I mean gravel blasters)

Really there is more commonality about the use of laterite clay and
other clay than we're giving credit for in this discussion and that's
something Jeff mentioned to me privately. I think all of the methods of
aquarium husbandry are saying use a mineral clay material, high in iron
(and maybe having a few other nutrients), with a relatively low amount
of NP fertility and a relatively low and stable organic content. (well
Dupla would have little or no organic content). There is a commonality

> Maybe we should reduce this discussion to a simpler question:
> I hope you have looked at the photos on my web page. Do you think my
> aquariums
> exhibit good growth?

I can't tell anything about growth rates from a single picture unless
there was a timed sequence of them. But I'll stipulate it because you
tell us that. Actually I was hoping to see some new pictures there
George. I'd like to see that C blassii you mentioned. It sounds like a
prize winner!

> If you don't think my aquariums exhibit good growth then we have nothing
> more to
> discuss because we have no fundamental basis for a meaningful dialog.

> And if I did have a number of, say, "0.385 liters per hour per meter^2", what
> possible good would it do? Again, if you don't know what to do with the
> answer,
> there is no point in looking for one.

If you don't know what to do with the numbers, how do you expect to
support your hypothesis that heating cables cause a large proportion of
the plants nutrient needs to be drawn into the substrate. ;-) Or is that
not what you're saying?

> >If you have no experimental values, then
> >please do feel free to quote Reynolds Numbers and fluid mechanics
> >formulae at length. Be sure to mention the co-efficient of thermal
> >expansion of water and the resulting hydrostatic forces. Don't forget >to
> factor in the viscosity of water and the average path length >between
> particles.
> If you would put down your "Encyclopedia of Physics Terms" for a minute and
> read
> a book on thermodynamics, you might realize that there is no data relating to
> the properties of the substrate in question. Even if there was empirical data
> for water+gravel+laterite, the computations for convection currents are
> intractable.

I don't see how I can explain it more simply than referring you to the
Reynolds Number which is the dimensionless number relating the ratio of
inertial to viscous forces in a fluid flow regime. In the substrate the
viscous forces dominate. Convection exists because of inertial forces,
not viscous ones. The modulus of thermal expansion of water is low and
the resultant pressure differential is very small. Now we come to the
mechanics of the heat engine, the transfer of energy involved in motion.
The ratio of heat transfer by radiation and conduction far far exceeds
the transfer by convection in this case. So the flow rates involved must
be vanishingly small. I doubt that any of us could come up with a
mathematical model to predict it but measuring it experimentally
wouldn't be hard at all. We've already discussed that experiment.

This discussion is so arcane that every one must be about ready to pinch
us! I can't even think up any decent puns. I think it says something
about us that we invest so many minutes everyday in this discussion.

I agree, there seems little point in continuing the argument. maybe
there is a little old lady in Tallahasee who hasn't made up her mind
about heating cables yet and this last post finally convinces her to
take up knitting as a hobby which actually soothes the nerves. ;-)