REPORT: October 2009
NATURAL SWIMMING POOL
using Flowform™ eco-technology in Horowhenua, New Zealand
Introduction
The swimming pool is a small domestic pool, with a figure 8 shape about 9 m long and
6 m wide. It is about 50 sq m in area and 1.5 m deep. It has been designed to
mimic a stream pool, with re-circulating water passing through a small wetland, a
Flowform cascade and a holding margin pond. There is about 300 mm of river
gravel on the bottom, and the Flowform cascade provides the stream sound effects,
as well as their regenerative and energising functions.
No chlorine is used in the pool, and the design indicator criterion was that frogs would
live in the pool. The pool remains very pleasant and cool even during hot summer
periods, and is really refreshing to swim in. We built it because our kids wanted a
swimming pool at home, rather than having to drive to the local river — and we were
interested in trying out a wetland-based pool, but one more like the pools of the fastflowing
gravel bed rivers of New Zealand.
Overview
The plan and section of the pool shows its overall layout and the recirculation system.
A small submersible dewatering pump takes the pool water, through perforated pipes
in the gravel layer at the bottom of the pool, and delivers it to bottom-up flow filter
ponds of gravel and reeds. From these wetland ponds, the water flows down a vortex-generating pipe, to the Flowform cascade, into the holding pond and back
into the swimming pool.
The pump flow rate was chosen to match the Flowform flowrate capacity, otherwise
the design was based on an overall pattern approach. The system, thus, has the
features of a stream environment, linked together in a specific arrangement. It
includes:
• an area of flow through a gravel matrix with water reeds on top (of the
wetland filter ponds);
• a still water holding pond of floating plants, like a stream backwater (of the
lower pond);
• a gravel bed in the main swimming pool;
• and a pulsating ‘superstream’ Flowform cascade, like a stream riffle
flow, upstream of a deep still water pool.
The pond areas are quite small, compared to the main pool size, and the vitalising and
energising action of the Flowform cascade is important in the maintenance of water
clarity and purity of the whole system.
The area around the pool has been planted with a range of species, from grasses, to
shrubs, to small trees, to give rise to a complementing outdoor space. River stones
have been used as a visual connecting form between the ponds and pool. The arch
bridge over the centre of the figure 8, has been a platform for much fun — on and
under the bridge — and the narrow connection under a bridge gives rise to two water
spaces. The bridge is also the access to a shade gazebo, and a more sheltered area
on one side.
Maintenance
The swimming pool has been in use for many years, and throughout has provided a
refreshing swim in a pleasant and restful environment. At the same time, it has
provided an interesting place for our kids to swim and play in, and an especially
exciting place for our dog.
We have not tested the water for bacterial loads, but have never had any problems.
Our younger daughter especially appreciated the lack of chlorine, as she was affected
by the chlorine in public and school pools.
The main maintenance issue is the build up of algae on the sides of the pool. Any
build up on the Flowform units is easily controlled by turning off the water
recirculation for a short time (when it is warm and dry).
To manage the algae in the pool, we dose it with both alum and gypsum. This was
based on research in Australia on how to make small water holes drinkable in
droughts, and is very effective. Essentially, it starves the algae of phosphorus, and
coagulates and settles the dead algae out onto the gravel bed. It is much cheaper
than chlorine-based algaecides, and very much more effective — and unlike the
chlorine products, does not affect the frogs.
We do clean off some of the dead algae from the bottom, and occasionally add
microbial preparations to break it down and allow it to be worked into the gravel
matrix on the bottom of the pool. natural quality and feel.
Flowform cascade
Lower end, with the holding pool below
The Author:
Gary Williams lives on a small permaculture farm in the Horowhenua, New Zealand,
with his partner Emily. It has a diversity of garden, farm, forest and wilderness, and
we use an organic management approach and the practices of biodynamics.
He works from home as a consulting engineer on water and soil resource
management, and provides advice, design and supervision services to a wide range of
clients from individuals to councils and government departments.
His latest book, "Out of the Helix", is a series of (word & picture) essays about cultural
transformation, and how we can bring about the shift in world-view required to
achieve a healthy, just and sustainable way of life.
If you want to contact him please email us at info@flowform.net
Source ............... http://www.flowform.net/files/Natural-Swimming-Pool-by-Gary-Williams.pdf
Further details from www.flowforms.com
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