Convert Your Eco-Unfriendly Swimming Pool into a Biologically Active and Attractive Fish Farm!
Animal Forage, Aquaculture, Biological Cleaning, Fish, Food Plants - Perennial, Food Shortages, Natural Swimming, Plant Systems, Urban Projects — by Craig Mackintosh July 21, 2009
Could converting swimming pools into fish ponds be another way to increase food security as we head out onto peak oil’s downhill slope?
A Permaculture fish pond in development
Swimming pools get a bad rap in enviro-circles, and for good reason. They cost a great deal to construct – using a lot of CO2 intensive materials in the process – they waste huge amounts of water and energy for maintenance, use chemicals to keep them clear and ’safe’, and they take up a lot of space that could be utilised for more productive purposes (like growing veggies!). Many people also just find them a lot of work to look after, which is especially annoying when their usage is often only seasonal at best.
But, what if you’re already lumbered with a pool and are trying to make the best of the situation? Maybe it came with your property, or hindsight has kicked in after you’ve shelled out thousands to install something you almost never use…. What then?
Some simply drain their pool of water and leave it at that. Although that is an option, it isn’t a particularly attractive one, and the pool interior will still require periodic sweeping and cleaning if you want to avoid raised eyebrows from your mother-in-law and other guests.
Is there anything you can do? Is there a way to use the pool while maintaining aesthetics and perhaps even bringing some other benefits with it?
A couple of days ago I stopped in at the home of Vanessa Fernandes (a former PDC student of Geoff’s) and Justin Sharman on Australia’s Gold Coast – to check out a rumour I’d heard of their swimming pool conversion. It was a fascinating visit!
Permaculture gardens and the pool blend beautifully
You see, about eighteen months ago, after a little contemplation and research, Vanessa and Justin determined to make better use of the big watery pit in their back yard. They decided to turn it into a biologically active fish pond!
The work is still in progress, but is already, in my opinion, a seriously superior version of what they had before. If a pool-to-pond conversion is done well, aesthetics can improve dramatically, and you can also end up with a regular supply of fresh chemical-free fish for the kitchen.
Eating from the pool didn’t seem to be the primary goal for Vanessa and Justin, but rather to create a closed loop biological system that would add beauty and diversity to the rest of their Permaculture system.
How they did it
After draining the pool, they set to cleaning it of contaminants by scrubbing the inside with vinegar and rinsing it clean. This is important or the fish you introduce could die. Before introducing fish, however, plants need to be established, as well as the all-important oxygen-generating algae. Algae forms on its own when allowed, and the best plants to introduce are those you’ll find in natural freshwater environments in your area (lakes, ponds, rivers) as these are best suited for your climate. Justin and Vanessa even introduced a couple of plants that are regarded as ‘pests’ by many government authorities – like salvinia, a fast spreading floating fern. Rather than a pest, the plant serves a purpose here as chicken feed, and its characteristic of spreading fast just means the chickens have a good supply of it!
Another plant introduced is azola – which is very high in nitrogen due to its special relationship with a nitrogen-fixing cyanobacterium. This makes it an exceptionally good mulch (azolla is said to increase rice yields significantly – "as much as 158 percent per year"). Of course, they also introduced plants that are great for human consumption – like kangkong, water chestnut and watercress.
The upside down crate in the water acts as a chicken self-rescue platform, in case
one chicken pushes another in (out of spite), and the hapless victim needs a way back out
At the moment the pool supports about a dozen silver perch ("plate sized", Justin said. "About 4-8 kilos of fish weight"). These are native to the region. The fry you can see below are munching on bread we tossed in to tempt the bigger guys that like to hang out in deeper water. I was hoping they might come up an impromptu photo shoot. The adults did make a showing, but they must be seriously camera shy, as they’d only lunge at the bread and disappear before my trigger finger had a chance to move at all. As we had another pressing engagement, I didn’t spend more than a few minutes on this, so forgive me for not supplying a picture of the final ‘product’. I guess it’s yet another fish-that-got-away story….
Baby fish snack on bread that was thrown in to attract the larger fish further down
At the moment the pool is essentially a closed loop biological system. The plants feed off the nutrients supplied by fish and bird droppings, the fish feed off the plants and insect larvae (like dragonflies, etc.), and the algae regulates the CO2/oxygen levels. Zooplankton and mollusks (snails) feed on the algae, the crustaceans (shrimps) feed on the zooplankton, and the fish feed on the mollusks and the crustaceans.
Oh, speaking about snails, if anyone spotted the blue hoses at top and thought I really should have pulled them out before taking any pictures, let it be known that I was going to do just that, but got stopped in my tracks. These hoses also serve a purpose – snails cling to the outside, and also live inside the hose, and it’s from these hoses that the fish like to feed.
As mentioned, algae is very important for the health of the pool – but you can have too much of a good thing. Algae blooms are to be avoided as they can suffocate life in the pool. A balanced algae population can be regulated in three ways: 1) reducing nutrient input (i.e. harvest some fish), 2) reducing light (i.e. add a translucent shade, or a living vine, over part of the pool), or 3) simply scoop some algae out if you get desperate and use it for mulch or compost.
The biggest thing stopping a decent increase in the fish population is oxygen. To regularly eat from the pool, Vanessa and Justin would need to incorporate a water filter/oxygenation system – which is something they’re looking at doing next. As you can see from the pictures, the water in this particular pond is rather ‘natural’. A biological filter would make the water clearer – so, if you wanted, it could still retain the pool’s original purpose (swimming!). Increased oxygenation also tends to keep algae from getting out of hand.
A bio-filter doesn’t need to be too complicated or expensive. Water could be pumped out of the pool and through a gravel trench, and then back into the pool (a solar pump could be utilised). As the water passes through the gravel it gets filtered/cleansed (by the algae that will develop there) and oxygenated. Reeds growing on the gravel aid in making the biological filter itself a closed system.
As well as the general aesthetic and the potential for increased food security and health, pools like these also contribute to the health of the garden in general as they attract a greater diversity of wildlife. Vanessa and Justin now have regular visits from predatory creatures, including white-faced herons and even the australasian bittern, a threatened species.
Essentially, a pool like this is a great example of the very essence of Permaculture – working with natural synergies, and finding ways to make them work for ourselves and the environment. Where modern agribusiness concentrates on chemistry, Permaculturists deal in biology. Instead of reductionist science, which would take just one element and pull it apart to its base chemical ingredients before we look up thinking we understand something, this kind of management takes a broader view.
This reminds me of an excellent passage that brings this thought home well:
Working with living creatures, both plant and animal, is what makes agriculture different from any other production enterprise. Even though a product is produced, in farming the process is anything but industrial. It is biological. We are dealing with a vital, living system rather than an inert manufacturing process. The skills required to manage a biological system are similar to those of the conductor of an orchestra. The musicians are all very good at what they do individually. The role of the conductor is not to play each instrument but rather to nurture the union of the disparate parts. The conductor coordinates each musician’s effort with those of all the others and combines them in a harmonious whole.
Agriculture cannot be an industrial process any more than music can be. It must be understood differently from stamping this metal into shape or mixing these chemicals and reagents to create that compound. The major workers – the soil microorganisms, the fungi, the mineral particles, the sun, the air, the water – are all parts of a system, and it is not just the employment of any one of them but the coordination of the whole that achieves success. – Eliot Coleman, The New Organic Grower, p.3, 4.
Justin and Vanessa’s back yard is not only a productive permaculture garden, but also an extremely beautiful wildlife habitat. I think my camera and I will have to stop by again sometime….
Resources:
Justin gave me a few resources that they found useful for their pool:
- http://www.biofilters.com/webfilt.htm – things that a bio filter does
- http://www.beadfilters.com/downloads/printablecalc.pdf – some things that you need to consider when you are sizing a bio filter
- http://www.scielo.br/scielo.php?pid=S1519-69842002000400019&script=sci_arttext – "water hyacinth is one of the many plant species we use as a low impact bio filter. When we harvest it, it makes a fine fungal based compost. We use azola as well."
Comments (13)
very inspiring… great job!
Comment by maghi85 — July 22, 2009 @ 2:53 am
Way to go guys! Nice to hear your doing so well and keep up the good work. We’ll have to come see your place next time we’re in OZ.
Comment by Jesse — July 22, 2009 @ 10:25 am
What a good job you permi’s surprise me every day – and it looks more in-tune with the environment than a blue sparkling pool! Just have to add gravel grow beds to filter the water – the fish waste can feed vegetables, check the forum at http://www.backyardaquaponics.com
Comment by David — July 22, 2009 @ 8:53 pm
Awesome work!
This is the future of suburbia and the urban houses…
It is these kind of efforts that will lead the way forward.. keep up the great work and please document and share your experiences with us all.
peace
Comment by Ernest Truman — July 23, 2009 @ 6:03 pm
You’ve inspired me. This is great!
Comment by Merry Hall — August 1, 2009 @ 12:09 am
I have had my pool/pond converted 8 mths neighbors now complain about mossies, which are a problem .. how do you control mossies Ihave some plants floating salvinia and about 17 young silver perch 11 fingerlings 6 slightly larger.. water quality looks good.
Comment by bill — October 1, 2009 @ 2:15 pm
Hi Bill
all those mosquito larvae should have been eaten by your fish, just make sure your fish have access to them.
Comment by Geoff Lawton — October 1, 2009 @ 5:58 pm
Gday bill sorry it has taken so long to reply but I have not had my eyes on the link for a while and life takes over sometime.
I can also recommend that you plant out you step area with a range of different plants, reeds are great and anything like persicarius kang kong etc etc diversity is the key.
I source my plants from healthy systems in my local area, when you do this you are also importing lots of micro flora and fauna. This will eventually attract dragon damsel and may fly’s as well as a host of other beneficial insects, the reeds are important as these insects spend up to a year in the water in the nymph stage, the nymph will provide excellent mozzie control for you as larvae is a primary food source. Some times the silver perch can be a bit lazy about surface feeding and the mozzies use the shape of the leaves to cradle their own brood, give the salvinia a good shake up to disturb this and like Geoff says that will give access of larvae to your fish. I also have other little guppy style fish which breed like flies and munch on the larvae and any excess food on the surface; the silver perch do not seem to eat them at all. The dragon fly nymph then climb up the reeds to morph into an excellent beneficial air force that will patrol your garden and pool.
Bidyanus bidyanus start with a basic diet of zoo and phytoplankton’s mixed with molluscs then move onto green diet plants algae as they grow .It’s important to purge your fish for a week or so in a smaller tank of clean water with a saline solution about 5% this will make the fish a lot tastier. The primary industry website in nsw has excellent research on all this and they have a great research station in Grafton.
Best wishes to all
Justin
Comment by Justin — October 27, 2009 @ 11:28 am
Wonderful presentation! There is one thing I like to hear.
Before you converted your pool into this beautiful permaculture garden fish pond, did you put some gravel/ sand onto the pool floor to make its bottom shallower for kid’s saftey? With many thanks, Yan
Comment by Yan Park — November 14, 2009 @ 7:47 am
Yan Park’s question is a good one…after the pool has been scrubbed, how was the base prepared. Pools can be deep. Sand ? gravel ? Mud ? Were structures added on which reeds, other plants could grow in containers ? Why was the existing pump abandoned – is water circulation unnecessary or would the algae clog the filtration system ?
Comment by Rob — January 4, 2010 @ 5:46 pm
Very inspiring. I would like to do a similar conversion and wonder if I could visit this site and get some guidance.
Comment by Joya-Rose — February 2, 2010 @ 10:51 am
Great project. Well done. Although salvinia and azola are useful for feeding your chickens, they are declared invasive weeds and should be replaced with native, non-invasive weeds. The lovely herons and bitterns that are visiting your pond will transport salvinia to rivers, creeks and other water bodies around the Gold Coast. Unfortunately, the weeds we plant in our backyards never stay there. There are some great websites showing the wide range of native aquatic plants suitable for the Gold Coast. cheers!
Comment by Deb Metters — February 4, 2010 @ 12:45 pm
Absolutly brilliant!Loved all the fantastic info. We are half way through a pool to pond conversion. The pond has few plants as of yet but plenty of algae and I think is almost ready to add fish I still need to do some research on filtration. We have dragonfly nymphs and water scorpions that have made themselves at home, so far we haven’t had a problem with mozzies although they like other sources of water on our property like underpots etc. I have been working on a food forest and Land for Wildlife project on my 2 1/2 acre property and the very helpful Land for Wildlife fellow Stuart Mutzig forwarded this link to me to help with my goal. If anyone of like mind is interested in coming to have a looksee and exchange ideas you are more than welcome. I live at Caboolture and you can email me on mamago251@gmail.com.
Once again great job guys!
Comment by Luisa — February 6, 2010 @ 12:31 pm
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