Humus vs. laterite

> From: Stephen.Pushak at hcsd_hac.com (Stephen Pushak)
> Thank you for the Jim Kelly article Shaji; it's extremely interesting.

One thing that was not resolved the first time this article appeared
was "what degree of CEC is sufficient for good growth?".  The blind
assumption was made that "more is better".  I don't hold with that
simply based on experience - we only have laterite (lower CEC) and
we have all the growth we could hope for.  

Other factors seem much more important in substrate additive
selection, such as:

 - will it discolor the water (peat, cheap "laterite")
 - will it stay in the soil (vermiculite floats)
 - will it decompose and cause problems (manure, rich dirt)
 - will it kill the fish (potting soil with built in fertilizer or
    weed killer)
 - will it add nitrates and phosphates (Brand X plant tablets)
 - etc.

Of course, being "Rich Beyond My Wildest Dreams" allows me to
disregard the cost.  Dupla works for me :-).