Snails, mayaca, phosphate kit

---------- Forwarded message ----------
Date: Wed, 15 Jan 1997 19:35:07 -0500 (EST)
From: DIONIGI MALADORNO <MALADORD%A1%RNISD0 at mr_nut.roche.com>
Subject: Snails, mayaca, phosphate kit
To: AQUATIC PLANTS <Aquatic-Plants at ActWin_com>

 "David W. Webb" <dwebb at ti_com> wrote:
<<<<<Subject: Re: Apple Snails
...In my tanks, apple snails will only eat dead or dying leaves and roots.
They never touch the healthy leaves of any of my plants. ... If the
snails begin to feed heavily on a plant, I know there is something very
wrong with that plant.>>>>>

Well, I do not doubt that what you say is true with your tanks, but it is
also true that many snails sold as apple snails do voraciously eat healthy
plants. It happened to me twice. Now, it might be that they were some other
similar-looking type of snail, and the problem was my inability to recognize
a "true" apple snail, but if I recall correctly I read a few times
contradictory statements in the magazines and books about the compatibility
of apple snails and plants (just working off my memory, I might be wrong on
By the way, kayaking the Delaware river I saw several times some sort of
giant trumpet snail, up to 2.5-3 inches long, with a grey/brown shell. Has
anyone ever kept them (with or without plants), and does anyone know what
species could they belong to? I found them mostly in shallow areas of the
river with pebbles and no plants, but since the heavily planted areas are
quite deep, I cannot exclude they live there as well.

During a recent trip to Italy I saw in an aquarium store a Tropica plant
labeled as Mayaca sellowiana. Does anyone know how does it differ (origin,
water requirements) from the M. fluviatilis I have been able to find here in
the US? The leaves seem slightly thicker than M. fluviatilis, but otherwise
it looks identical.

I have been using the HACH orthophosphate kit PO-19 (cat. no. 2248-00),
obtaining in my main tank results consistently higher (1.5 mg/l) that what
the tank conditions would suggest (virtually no algae or cyanobacteria
growth, except for very very small, occasional patches on some floating
plants only). Plant growth is very good, nitrates are at 5 mg/ml (with PMDD
supplementation: thus they should not be the growth limiting factor for the
cyanos). A little ago I tested the kit with distilled water, obtaining a
reading of 0. I have the following questions: am I correct in using an
Orthophosphate kit? Are the commonly quoted "recommended limits" expressed
as orthophosphate, or as total phosphorus (in that case my readings should
be divided by three according to HACH)? Is anyone aware of possible
interactions between the kit reagents and something else? I am curious to
find some possible explanation to this apparent inconsistency. Oh, yes, I
also used the terms orthophosphates and phosphates without really knowing
the difference between the two....if anyone can clarify the differences, I
would appreciate it. Thanks


PS Back at home, I checked the recently published TFH book on apple snails by
Perera and Walls. Just one eloquent quotation (page 40, "feeding"): -Certainly
if they (apple snails) can eliminate the water hyacints and Pistia from entire
caribbean lakes, they have the ability to eat all the plants you might put in
their aquarium-! Maybe the snails of David are well fed with fish food
leftovers, and they now consider plants a less appetible choice. Dave, are you
by any chance writing about ramshorn snails instead? Those DO eat only decaying