[Q] What to mix in my substrate?

On the topic of substrates, as has been a popular thread on the list this

 I currently have a 55g with a substrate mixture of a 1/4" coating of
vermiculite, peat 
 spread over that, and about 30 pounds of sand over the top of it all.  My
 is this:  Is this sand going to hold pockets of water, generating lots of
nifty rot and
 degeneration, i.e. ammonia?  I am thinking on just laying down
vermiculite, peat and
 some river-gravel (I am going for the 'natural' look :^) ) - would this be
a valid substrate
 for my plants?  
 The tanks inhabitors are:
 1 7" Elephant nose
 7 tiger barbs
 2 upside down cats
 2 octos
 ? those blue colored (trumpet?) snails...
 I have a bunch of java fern, some alluminum plants (I know they are
terrestrial, but
 I bought them about a year ago, before knowing anything about plants, and
 pretty much thrived in my tank!) a couple of swords and lots of java moss
on my
 Can anyone give me a good idea as to what to put under this all?  I would
 like to hear suggestions on substrate content.