Final Steps - December 2010

The final steps in the project have been to add landscaping around the edges of the pool which over time will add to its natural look. The pond itself is clear and has become a haven for local wildlife. Already it is full of tadpoles, buzzing with colourful dragonflies and the local bandicoots (Australian marsupial) are drinking at the edge of the pool. I have covered the river sand with a thin layer of finely crushed quartz (known locally as rainbow stone) and it's a very inviting environment. The plan is to still be able to wade in and cool off on those really hot summer days and I think this should be OK.

 
We also planted the in-pool grow bed with a selection of water lillys, water iris and native sedges. These have responded very happily to their new environment and we had the first lilly flower last week.

  In - pool grow bed with water lillies etc

The grow beds were planted about a week ago with a range of vegetables - lettuce, Chinese greens, capsicum, cucumber and rhubarb. The grow bed closest to the pond we have reserved for strawberries. We have put in a few native minnows to start with and plan to stock the pool with our first lot of fish and marron (local fresh water crayfish)  in the New Year.

Planted grow bed - strawberries

Pumps and Aeration

Well this was a bit like the grow media issue - lots of varying opinion leaving me having to trust my own judgment.  Given the volume of the pool (now approx' 15,0000litres) and the need to filter that every 2 hours to keep the water quality high enough for some of the more temperamental fish species (ie trout), I was looking for something that could move a fair volume of water. I also had a fair amount of distance to cover with two of the three external grow beds about 6 metres away from the pool and at least 2 metres higher than where the pump sits.

The other reason I wanted a stronger than average pump was because I hoped to divert a percentage of the water away from the grow beds and return that to the pool via a large pipe running off a nearby pergola. This was a little piece of drama inspired during a recent visit to Spain where water gardens and water features are truly spectacular.


Anyway the end result was that the pump carried sufficient water to the three grow beds but not the arching aerator - I believe it is pumping well below its specifications and I plan to remedy that in the new year. In the meantime the return from the grow beds is  aerating the water but on a smaller scale.

Water returns to the pool from the two external grow beds

via a bamboo channel

The Spanish Folly

Grow media

This seems to be a constant source of discussion on aquaponics blogs and there are lots of arguments to favour different types of mediums. After a while I settled on local pea gravel (10cm diameter), more than anything it was price. The whole system was starting to eat into the hip pocket - especially after purchasing the grow beds. MY neighbour and consultant also used the pea gravel in one of his grow beds with good results. I'd also got a handful and tested the PH to ensure it didn't contain anything that might negatively effect the water quality.

I got a tip on washing the gravel off a local forum and bought an old fly-wire door which we shoveled the gravel onto in small lots before hosing it down. The washed gravel was then emptied into a wheel barrow and carted off to the grow beds. Four of us washed and moved 4cm of pea gravel one hot Saturday morning in late November.

1st grow bed full and in place

Grow beds 2 & 3

Grow Beds - external October 2010

Previous to the introduction of the aquaponics system I had a productive vegetable garden of approximately 60 square metres. The idea of the aquaponics is to compensate for a loss of much of this garden in the summer months when water is scarce. Initially I looked at building my own beds but given my work commitments and 'lets get it done' attitude, I settled on ready made beds. I sourced one from a local pool manufacturer and two other units from the local supplier ' backyard aquaponics. Both units were made from stabilised PVC but the beds purchased from 'Backyard aquaponics' (BA) were much sturdier.

The cheaper unit was to be positioned just above pool height inside the pool enclosure whilst the larger grow beds from 'BA' were to be housed on the old vegetable garden site and raised for easier access.  The old vegetable garden site is approximately 6 metres from the pool edge and I had to run the piping under the pool fence and paving.

The drainage from these three units would return via a common exit line out the existing pool ducts.

That was the original plan, but there were a couple of hiccups!

Excavation and piping for the first in line

grow bed - cheapie from 'Tank Master'

Raised grow beds courtesy of

'Backyard Aquaponics' with in-ground Tomatoes

( on drippers) planted to reduce their visual impact.

Filtration - In - Pool Grow bed - September 2010

As well as filtering the water through the standard grow beds (3 in number), I decided that the volume of water was large enough to warrant additional filtration and the cheapest method to do this was to incorporate a section of the pool as a gravel filter itself. This section lay behind the sand bund and water would be filtered from the open section of the pond through pipes (on their way to the external grow beds - through a one way valve and out 6mm holes - 10 cm apart) at the bottom of this section. This in- pool filter would house the water plants and nutrients would feed up through the gravel to the plant roots. I've seen similar ideas in swimming pools where people wanted to avoid chlorine or salt filters.

Reducing the Pool Volume - June 2010

We started out with a relatively small pool about 25,000 litres.  The first thing I did was drain the pool which can be dangerous if your pool is embedded in clay soils - the clay swells with water and the empty pool collapses. Luckily my pool was surrounded by a supporting framework of yellow brickies sand and the pool held its shape as the water drained.

I then got a load of local river sand - approximately 15 cubic metres and distributed that into the bottom of the pool to reduce its size to around half the volume.  I also created a bund to one end (a river sand wall) which I wanted to use to section off from the fish an area for water plants which I'd read were usually destroyed by larger fish.

Early Days

Prompted by increasing environmental awareness, diminishing demand for the use of the swimming pool after the kids left home and the exhorbitant price of fish - the idea for converting our backyard swimming pool into an aquaponics system started to take shape.

Having a neighbor who was already into this movement was an added advantage, but I couldn't find too much information on people who were converting their swimming pools into these types of systems - most people bought standard sized units from professional aquaponics suppliers which were efficient but frankly very ugly and not very nice environments for the animals (fish).

I was keen to create something aesthetically pleasing as well as practical. Below is a photo of the swimming pool before we started the conversion.