Re: soil works, Dupla doesn't (for me)

>The brown edges that spread inwards do not sound like any kind of nutrient
>deficiency that I know of.

Really, maybe I wasn't describing it vividly enough.  The leaves simply
faded (again, starting at the edges and moving towards the center).
It's not like there was some sort of film or anything else, they just
turn yellow, then brown, and eventually transparent.  No holes develop,
except, of course, in the very last stages where the leaf is very
fragile and the slightest thing can rip them.

Obviously (due to my experimental results), the problem is a deficiency
of something that is present in soil, not a water toxicity, but is this
really what a toxicity reaction is like?  (Just curious - if I do see
such symptoms again that aren't fixed by this technique, I'd like to know
what fixes it.  I've seen crypts melt before, and the symptoms are
similar, but the process is *much* quicker and it happens to the
entire leaf at once.)

I saw a posting some weeks ago that listed the symptoms of all nutrient
deficiencies and my problem could have been any one of about 10.

And yes, when I said "potting soil" I meant dirt I pulled out of a
potted plant I had that was handy (very scientific, no :-) So anyway,
the soil I used is a mix, mostly composed of topsoil, plus some
organic material.  I've tried heavy organic substrates before (peat/soil
mixtures), but always ended up with a major H2S poisoning & algae festival.
Would it be correct to infer from what you've said that peat is not
fully composted and hence is a far bigger risk for H2S buildup than
bottom-of-the-compost-heap-compost, earthworm castings, etc?

Finally, while I do intend to do more with potting of problem plants,
I was thinking about alternatives to potting because some plants just
don't take to pots (e.g. valisneria, lileopsis, other ground-covers...)

In my soil-substrate experiment tanks, I noticed that pulling up a plant
was virtually a no-go, because the soil would cause a major cloud and,
after a few such events, your carefully blended substrate layers would
become a complete mishmash.  That's why I was thinking about this notion
of using a small amount (tantemount to how much laterite dupla recommends).
Although there's a bit of a cloud when I uproot a big plant, it's nothing
like the problems I had with the soil tank.

Another thing I might do (as an alternative to potting and to tearing down
my tank and redoing the substrate), would be to take some soil and wrap it
in nylon (or some other permeable material), and stick that in the gravel
underneath non-pot-friendly plants.  This has its drawbacks (esp if you need
to uproot in the vacinity of one of these balls.)  Fortunately, all of the
plants I keep now that look like they might benefit from soil are imminently
pot-able, so I won't have much need to try this out.

                                        - Steve
(In Austin, where it's nothin' but hot.)