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Re: Clay balls

Thomas Vickers wrote:
> >How many grams in a tablet? I don't think you should use a full tablet
> >all at once. That's a pretty large dose. Start with one or two clay
> >balls or make small balls. Don't use too many. You can always add more
> >later.
> i was figuring using one tab to make 5-6 small clay balls.
> I don't think I want to use more than 1 tab total, if that, at any one time.
> TV

It really depends upon how large the tablet is and how much it weighs. A
large tablet could be anywhere from 5 to 10 grams! That's a huge amount
of fertilizer. If you have a postal scale, you can weigh 10 or 20
tablets to get a pretty good idea of their weight per tablet. For
comparison, a Canadian quarter weighs 5 grams and a dime weighs 2 grams.
You can make a crude balance from a ruler and a pencil.

Here is some information from my web pages (all of which you should read

Enriching the Substrate 

"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 5.7 grams)"

These clay balls (50mg of fertilizer) are too strong to be used in large
quantities such as throughout the substrate during setup. Instead you
should probably use only about 200 mg (0.2 grams) in total divided
amoung about 10-20 balls. That would give you 10-20 mg per ball (or
pellet) which is about 2-4 pellets of 14-14-14 fertilizer. 200 mg is
very roughly about 1/20 tsp of the pellet fertilizer I use. Recall that
one clay ball with 10 pellets has 70 mg of P2O5. If that were dissolved
in 100 litres of water, you would have 0.7 mg/L. Its enough to grow a
very very large plant (which is mostly water in composition).

Its not necessary to use 14-14-14 fertilizer. In fact, most people
prefer to use the Fern formula Jobe's stick because it has such a low P
content. In houseplants, it doesn't matter if the P ratio is higher and
such high P formulae are used for stimulating blooming. 14-14-14 just
happens to be what I have readily at hand. I add a little more N in the
water column by adding K2NO3 in my mineral mix. This helps to ensure
that there is never a shortage of N which can lead to poor growth,
chlorotic plants and diminished growth rates which can lead to a P
buildup in some circumstances. I think it would be fine to use regular
Jobe's sticks but keep an eye on the nitrate level.

A last point; Jobe's sticks contain "occluded" fertilizer. This simply
means that the fertilizer is embedded in a semi-permeable material which
prevents the nutrients from dissolving freely. That's the same point as
using clay balls; to prevent the nutrients from diffusing rapidly into
the substrate water. Sand and gravel substrates are fairly permeable to
nutrients and water, unlike clay mixtures. By clay I mean clay texture;
mineral particles smaller than 2 microns. Materials like kitty litter
and vermiculite, while they may be composed of the same minerals as fine
clays, are not by this definition clay. KL and vermiculite are highly
permeable. I don't know what the material is that Jobe's sticks are made
of. Anybody take a close look at them and hazard a guess? Could they be
Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!