This blog has been contributed by Hobart local, Jenny Calder. Enjoy!
In May last year myself and two friends bought a home in South Hobart with a glorious mountain view and plenty of sunshine (co-ownership – a novel way of housing ourselves – don’t rule it out). It also had a 10m long swimming pool, used over the last 30 years by the previous owners to operate a learn to swim business.
Our pool had begun to come alive! I made a trip to the Ridgeway Nursery and introduced a diverse selection of native water plants. I have planted them in pots, placed on top of various pieces of submerged plastic furniture, all from our friendly local tip shop. The plan is to fill one third of the pond with plants, which will oxygenate the water and use nutrients that would otherwise be used by slimy algae and pond scum. 
I have also introduced azolla and duckweed. Azolla is a free-floating, nitrogen-fixing, water fern, often seen with a red tinge on farm dams. It and its companion duckweed multiply at an incredible rate, and can be scooped off and used in compost. Being high in protein it has been promoted as a supplementary food for chickens. On experimentation, they don’t seem to like it that much, but they do like picking off the bugs and occasional tadpole that come with it.
The evolving ecology of our backyard water-body has been a fascinating process to watch. Six months on, the plants are growing strong and an increasingly loud chorus of brown tree frogs have taken over the night air in the summer time – I am amazed by how much noise such little critters can make! Tadpoles, water boatmen, back swimmers, tiny snails and other weird and wriggly creatures abound, and there are very few (if any) mosquito larvae (we had a pond-dipping and water bug identification afternoon to investigate). 
Dragonflies visit regularly, spiders have spun webs between the reeds, and a pair of wood ducks have made a once-off appearance. I have also planted several pots of mint in the pool, which are providing us with plenty of delicious tea, and we have also started stacking rocks and placing succulents around the pond edges to create hiding places for frogs and skinks. In the future I hope to install a small water pump to circulate the water through an external gravel and reed bed. This will further cleanse the water, and hopefully we can still enjoy fresh, chlorine-free swims!
Jenny adding more plants to the natural swimming pool. She’s wearing a wetsuit as it’s pretty cold in Tassie right now.
The pond and young orchard in Jenny’s garden – a blossoming hub or biodiversity
There are many inspiring more swimming pool naturalisation projects to be found online, such as this one. Another inspiring project is Garden Pool, where a family of four are growing most of their own food in an aquaponics system in a converted pool. One day I’d like to look into this too, but the short term plan is bringing biodiveristy into our backyard by creating habitat for some of the amazing metamorphic wetland creatures we share the planet with!
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Looks fantastic;