What’s the
Deal with
Zeolites
What is zeolite, and
how is it used in the
reef aquarium?Zeolites are a group
of aluminosilicate
minerals, and there
are numerous kinds,
which may have slightly
different properties. These
minerals have been used
for many years in freshwater
aquariums and ponds for their
ability to adsorb ammonia,
generally as an emergency
measure (in freshwater
applications, the media can
be ‘recharged’ with salt when
its capacity is exhausted,
as the sodium from the
salt exchanges with bound
ammonia).
Relatively recently, zeolites
have become used on marine
aquariums. There is still a
bit of mystery surrounding
exactly how these work, but
the general idea is that they
act as a combined chemical
and biological filtration media,.
Chemically, the media is
claimed to bind various toxins
and nutrients to active sites
on and within its structure.
As a biological medium, it
is thought that the zeolite
provides physical sites which
aerobic and anaerobic bacteria
can inhabit and that the
adsorptive properties of the
mineral optimise bacterial
action. For example, it may
bind ammonia in a way that
facilitates nitrification and
possibly catalyse subsequent
nutrient pathways that may
take place within the pores of
the media, and using carbon
sources may enhance the
various microbial processes.
How these specific zeolites are
affected by sodium from the
salt water isn’t clear (and in fact,maybe this is of no importance),
but manufacturers are cagey
about the exact make-up of
their proprietary blends of
zeolites. In any case, the media
appears to become exhausted
and / or clogged over time, so
manufacturers recommend
replacing it every few weeks.
It’s chiefly used as part of
a probiotic system in the
reef hobby, with several
manufacturers (for example
ZEOvit and Aquaforest offering
marine-specific zeolites). In
the ZEOvit system (which
popularised the use of these
kinds of media in the reef
hobby), the zeolite is a key
component alongside organic
carbon dosing, and is intended
to be agitated frequently torelease the bacterial biofilm -
this is then available as food for
the corals. This can be quite a
labour-intensive method and
requires some experience, but
it has shown to be capable
of producing extremely low
nutrient systems if done right.
It’s important to adopt any
new method such as zeolite
slowly, so as not to shock corals,
and follow the manufacturer’s
guidelines carefully.Q
A
Budding
Biologist
Hi - Not a standard
question Dave but
you are probably the
right person to ask!
As a Reef-keeper I’m thrilled
that my daughter has decided
she wants to be a marine
biologist. She is currently
looking at her options at GCSE
and it would be really good
if you could give us a bit of
advice about what she should
take alongside the science
subjects; we are thinking
beography and ICT?
Also could you recommend
a really good book for aQ
Rumour has it that Mr Wolfenden eats a bowl of zeolites for breakfast! [Ed.]