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RE: Clay Balls in the substrate

George Booth recently responded to a post made by Bill Terberg concerning
his clay pellet maker/insertion device:

>>Only with the greatest of good fortune
>>and or skill can one set up a layered high nutrient substrate without
>>having some significant control problems.

>Yes, diregarding the unnecessary "high nutrient" part, one is fortunate
>indeed if one has heard of Dupla and even more fortunate if one has enough
>skill to fork over bucks for the equipment. Oops, my cynicism is showing.

What does skill have to do with forking over the bucks needed to purchase
Dupla equipment? Skill is probably involved with earning those same bucks,
but in my experience, a fool and his money are soon parted <g> (at least,
that is the case with me!)

>>In another experiment,
>>fertilizer/clay pellets were placed into test tubes with a 1" layer of
>>gravel below and 1" layer above.  Within a day the clay pellets had
>>disolved and settled through the gravel to the bottom of each tube, no
>>matter how fine the gravel was.

>That seems like mighty fast dissolving and is contrary to observations made
>by other aquarists using clay balls, including myself (Duplarit-K in an UGF

I was one of those selected by Mr. Terberg to "beta test" (I guess that's
the term) his device when he first developed it. I did not have much of a
chance to actually use it until recently. I have a couple of "grow out"
tanks which I use to propagate plants. No fish are maintained in these
tanks, but they do get very good water circulation and periodic additions of
Seachem Flourish and Flourish Iron.

I have the plants in translucent plastic "tupperwear" type containers inside
of these tanks. As a substrate, I use a variety of materials, depending upon
the plants I want to propagate. One, in which I am trying to grow Dwarf Sag
(Sagittaria subulata) has a substrate composed of a one inch thick layer of
topsoil from a mixed maple-beech-oak woodlot. The soil is very sandy but
also very "black" and has a nice, light texture. Over the soil, I placed
about an inch and a half of plain quartz gravel. About a month and a half
ago, I planted nine S. subulata into this container.

In the past month and a half, the nine plants have become perhaps 99. There
are runners everywhere, and the growth of the plants has been very good. I
can see the roots of the plants very easily throuh the sides of the
container and they form a dense network reaching down into the soil layer.

During the past week, some of the leaves have begun to pale and have not
responded (yet) to an increase in Flourish or Flourish Iron added to the
water column. I guess, the plants have probably exhausted the limited amount
of nutrients in the small amount of soil in the container. Remember, there
are no fish in the tank, and Flourish is formulated on the assumption that
fish (and fish food) are present in a tank (to add nitrogen and phosphate).

I glanced at Mr. Terberg's device, and decided to give it a go. I have a bag
of "Red Art Clay" in the aquarium closet and all of the makings for PMDD, so
I mixed up some clay with a few pinches of the various nutrients in the
Homegrown Hydroponics kit plus some crushed granules of fritted trace
elements and, for good measure, threw in a pinch of Micronized Iron in as
well. The actual amount of fertilizer added to the clay was small and was
well mixed with the dry clay before I added enough water to form a stiff

I found the device fussy to use, but perhaps that is because I'd rather just
roll the clay into balls with my hands than use the device to make pellets.
I baked the resulting pellets (I think someone claimed that this would hurt
the nutrients but that's crap - a domestic oven can't get hot enough to do
much damage to them). When the pellets were completely dry and hard, I used
Bill's device to insert them into the substrate. Work's well enough, but the
pellets DO tend to dissolve very easily - they definately don't hold
together for long once wet. The water column was cloudy with suspended clay
particles (from the action of using the insertion device) after I was
finished. That was 12 hours ago and the water has cleared completely (I have
an Eheim 2252 Power Filter on the tank, and it is VERY powerful, so I guess
that is the reason the tank cleared so fast). It is of course way too soon
to tell if my injection of clay and fertilizer into the substrate will perk
up the plants, but I can say that the added clay IS visible (as a fine
powder) through the sides of the tupperwear containers - those little
pellets have fallen apart completely and are in the process of dispersing
within the substrate. I am not claiming this as a fault, just an

>We've observed the same thing in
>planted tanks.   This action  sets up a very fine layer of fertilized
>clay at the bottom of the tank which seems to be a more controllable
>situation than a massive laterite or clay layer.

This very same thing is seen to occur in a Dupla substrate, which, by the
way, does not fit the term "massive laterite layer".

O.K., seems that my experience and observation here is not unique - the clay
should probably dissolve and migrate within the substrate.

George, would you care to comment on "massive laterite layer" vs "Dupla
substrate"? I mentioned the other day that the useage rate for another
laterite product (Substrate Gold) is 3.7 times as much as Dupla recommends
for Duplarit G. Assuming of course that the laterite in Substrate Gold
(mined in the USA) is similar in properties and form factor as the Dupla
product (mined in S.E.Asia I believe), would following the higher
application rates be more or less effective? Substrate Gold also has an
additional fertilizer component which is absent in Duplarit G.

James Purchase