Re: Aquatic Plants Digest V2 #445

Two questions:

First, I have a "quarantine" tank which often doesn't have a fishy
denizen.  Since I've taken up plants, I've also begun collecting snails. .
. I don't want to play with bleach when adding a plant, and don't mind
getting my hands wet (I can't understand why people mind. . .  Just keep a
towel handy. . .  Anyway. . .)  So, when I spot a snail (but before
feeding the fish), I pluck it out and toss it into the quarantine tank
(unless it's so small that I can't pluck it, in which case it gets
crushed.)  Hey, it keeps the bio-filter in the quarantine tank going.

ANYWAY, the quarantine tank has become a growing-out tank for juvenile
snails, and I've grown at least three types.  I remember reading about
some snails which don't harm the plants (relatively speaking), Apple
Snails, perhaps?  Can someone suggest an internet reference, or at least
the names of the snails in question, so that I know what to search on?
What I'm looking for is a guide to identifying whether or not I have any
beneficial snails which I might put back into the plant tank.

Second question (yes, I know I'm a windbag.  Sorry.):
I have a slowly-developing algae that I can't identify.  It does not grow
on the glass, and I don't see it anywhere on the gravel, but it's
becoming common in speckled patches on flat-leaved plants. It has no
filaments or other growths; it just grows flat on the plants (although 
this may be from the Oto's shearing it flat.)  It does
not rub off with moderate finger pressure.  It is spreading very slowly,
albeit steadily.  Should I suspect a plant-based algae, or cyanobacteria?
It's not forming sheets, at least yet.  Any suggestions for i.d., or
online sources for reference to help me i.d. the algae?  I've read the FAQ
and browsesd the Krib, but can't seem to find what I'm looking for.

Thanks, all.

                                       --  Edziu