Others are so pungent your head involuntarily flicks
back at the slightest whiff and you explete "Ewwphh!" Your instincts do not
deceive you. That really smelly stuff can be as harmful as it smells and it is
certainly no good for any fish in the garden pool, nor is it any good for
going straight onto the garden.
The material that you have possibly scooped up in your hand is more alive than
any sci-fi alien gloop from outer space that is threatening to engulf the
whole of New York State. This garden pool putrescence is in fact a mixture of
millions of bacteria and the organic matter that sinks to the bottom of the
garden pond (and or gets pumped up into the filter system).
Those bacteria are busy digesting the organic matter,
which in the process gets broken down to its constituent chemical parts.
Originally it would have been plant material, dead algae or fish waste. Fish
waste equals fish faeces and uneaten fish food. Both of these consist of large
amounts of Hydrogen and Nitrogen linked in compounds and the process of
breaking them up into elements that are not toxic to the environment creates a
heavy load on the eco-system of the garden pool environment.
This means that a lot of bacteria and microbes need a
lot of resources, and those resources are available oxygen atoms. If oxygen is
limited, you get the wrong bacteria down there attempting to deal with the
problem and they tend to create a bit of a smell. It may not be as sentient as
'alien gloop' but it does tell you something. If there is a faint hint of
sulphur with a hefty ronk of ammonia or perhaps a waft of methane, then you've
got a population of bad guys.
Well they are not really bad guys..... They are
anaerobic bacteria that have their rightful place in the great tapestry of
things, but they are best kept at the back end of the process of breaking up
all this organic matter, that is, when most of the job is done. The guys you
really want first at the "Eat up All my Organic Waste Party" are aerobic
bacteria - they need 'air' (as in 'aero') to be there.
WHY ME?
If your garden pond stinks and your filter is foetid and you feel that you
have been inflicted with the wrong sort of 'gate-crashers' to your microbe
ball, make sure:
the filter system or the activity in the bottom of the garden pond has had
time to get going before being overloaded with fish. It may need a biological
'starter'.
The process of organic matter in the bottom of a garden pool effectively being
digested starts with a metamorphosis in part (especially the fish food and
fish excreta) into ammonia and ammonia compounds.
Ammonia is particularly toxic to Koi, as you know, which
ironically exude the stuff from their gills during metabolism anyway. Oxygen
dependent Nitrosomonas bacteria are hopefully there in the bottom of the
garden pool or in the filter medium breaking this down as quickly as possible
to nitrites.
Nitrites unfortunately are toxic too, but nitrobacter
bacteria move in to build these up to nitrates. The resulting nitrates can be
taken up and used by plants or can further broken down. This is when anaerobic
bacteria could come in to play by breaking up the nitrates and releasing the
oxygen and nitrogen.
Now if you haul this stuff out of your garden pond at any stage in the
process, it is either going to continue its natural break down outside, or if
it has reached the nitrates stage of the process, it will be the equivalent of
vegetable rocket fuel.
Most plants don't want rocket fuel, and if it is not
rocket fuel but still muck continuing its decomposition, there is a danger
that it will leech out goodness from the soil to aid the decomposition.
So the best place for it is the compost heap. Here it
can be diluted and watered in or, if it is thick heavy sludge, it can be mixed
in layers between very fibrous and straw types of material. Because this keeps
the collection of material open, oxygen is available to complete the rotting
down process of the material from the filter and it all rots down to a moist
friable compost.
As far as the compost heap is concerned, if the compost needs an efficient
'starter' for the rotting down process, nothing can be bought that is any
better that garden pond gunge with its mixture of bacteria, organic compounds
and nitrates.
IF THE WORST COMES TO THE WORST
If you have nowhere else to put it and it does not smell too bad, spread or
water it onto a bed of fairly vigorous shrubs or perennials. Disperse it as
much as possible and as it begins to dry, gently 'prick it in' with a garden
fork. This ensures that you haven't created a suffocating pan over the surface
of the soil and opened it up to the air.
In bulk, it is on the acid side of neutral. This would make it unsuitable for
the vegetable patch without being diluted by garden compost, but may by a nice
fillip for an azalea or rhododendron bed.
The
Pond Professor
Water
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