Veggie production- Tat soi

The fish production in these systems is almost a side product as it will take at least 9 months to produce fish of edible size.
In the mean time we expect to get many kilos of veggies.
The system has only been running for a little over 2 months and already we have eaten a fair few lettuce, pak choi and tat soi plants.
The first seeds actually went in before we got the fish as the system had cycled and there was enough nitrate in the water to support plant growth.
The total growbed area might actually be smaller that optimal for the size of the fish tank- If I find that the nitrates in the water build up to too high a level, (no real idea what that would be at this stage), I will probably add more azolla or duckweed to the fish tank and/or do a partial water change.
We decided not to grow or buy seedlings elsewhere but to simply sprinkle some seeds directly onto the growbed gravel. This seems to work really well- in fact a bit too well as we have had to do quite a bit of thinning once the seeds germinate.
The first picture shows tatsoi about a week after planting and the second shows the same plants after we have eaten the majority of those left in the initial clump and now about to harvest those which were transplanted from the original crowded area. Transplanting set the seedlings back about a week but in effect spread the useful growing season out by an extra week or two. The first picture was taken on 1st October 07 and the second on the 25th November 07 ie total time from planting to almost final crop about 8 weeks. We planted a new lot of seeds about a week ago so should have another harvest of tat soi in about a month.
In the background of the second picture you can see flame lettuce- this was planted about the same time as the initial tat soi but is very congested and probably needs a lot of thinning for individual plants to get away.

Fish

The choice of initial fish was partly determined by what was available and by what species could survive the expected lower temperatures we get here in wintertime.
While I was waiting for the weather to warm up I placed a recording max min thermometer in the fish tank and recorded reasonably stable temperatures in the water. However the low point of 7.5 degrees Celsius means that most of the fish I thought I would like to keep would not be viable.
Help from the Backyard aquaponics forum lead me to decide on Tandanus tandanus ( the Australian eel-tailed catfish) and Bidyanus bidyanus (Australian silver perch).
I remember eating catfish years ago and being very impressed with both flavour and texture so that was a happy discovery. Silver perch is considered one of the really successful species to grow- very hardy and also very good eating.
I managed to find a source of supply for the catfish and so went to the Murray Cod Hatchery at Gumly Gumly , near Wagga,
Murray Cod Hatcheries
RMB 626 Sturt Hwy Wagga Wagga NSW 2650
ph: (02) 6922 7360
and bought 180 fingerlings. They were about 40 to 50mm long at the time. Greg , the owner of the hatchery will possibly have silver perch late this year and if so I plan on buying about 100 little ones then. Greg also reckons they will live quite happily with the catfish without either species wanting to eat the other.

The fish were floated in the tank in the usual way and then when tipped into the water they simply disappeared as the water was so muddy.
This was cause for some concern as I was worried that I couldn't see the fish and so had no idea if they were feeding or not. By the time the water cleared enough for me to see the bottom I was a bit distressed to see a couple of bodies there. I fished out about 10 or 12 dead ones over the next couple of days. I have also removed a couple more since. It is almost impossible to estimate what my actual losses were as the fish are still quite small and difficult to see. Some have grown quite significantly however and there is quite a range of sizes. A few are about four times the body mass of the smallest. I expect uneven growth and it is actually a benefit as it would be a bit of a problem to have all ready for eating at the same time.
At this stage they are feeding on 2.5-3mm sinking pellets for Australian Native fish as the main diet with supplements of live Daphnia and mosquito wrigglers when I can catch the same.

The pictures were taken when the water was muddy and I managed to catch a few who were silly enough to come to the surface. I am no longer able to catch them as they can see the net coming and escape like little rockets.
They look a lot like tadpoles and swim like tadpoles as well.

Initial nitrogen cycle

For the system to work properly it is necessary to establish the bacterial film which will convert the fish waste into something which the plants can utilise.
This film will grow primarily on the surface of the gravel in the growbeds and would have happened naturally without intervention from me. However I wanted this to happen as soon as possible so I took a big sponge filter out of a filter in another fish pond I have and rinsed it out in the water in the big 4000 litre tank. I then got some dead fish we had in the freezer ( flathead fillets and squid which had been forgotten) and suspended this in a couple of nylon bags in the fish tank water for about 3 weeks. I also bought a comprehensive test kit so that I could monitor the progress of the establishment of the cycle.
Unfortunately I clearly missed the peaking of the ammonia production and so don't know how long that took to happen. By the time I got around to testing for all Ammonia , Nitrite and Nitrate the levels of the first two were basically trace to nil. Nitrate was quite high and has remained so ever since. This is not bad as the system had clearly cycled and all ammonia is being converted to nitrate before it has a chance to hurt the fish.

Aquaponics- what does it mean?

The word is a combination of Aquaculture and Hydroponics.
Basically it is the setting up of a self contained system which uses fish to produce nutrients for bacteria which convert ammonia compounds into nitrites and then nitrates which are taken up by plants which in turn purifies the water and make concentrations of fish which would not otherwise be possible.
If all goes according to plan I should be able to raise at least 100kg of fish per year in 4000 litres of water. That is 2.5kg of fish per 100 litres of water which is actually a fairly conservative stocking rate.
Needless to say the system needs to be carefully balanced and that is the real trick. If any part of the scheme fails the whole thing will fall over and neither fish nor plants will thrive and/or survive.
Versions of aquaponics have been in use for thousands of years so it is nothing new.

Shed Modifications

The shed is a 15 metres long , 9 metres deep and about 4 metres high and is my main storage area for machinery and general junk.
The western end already had a couple of tray of translucent polycarbonate in the roof but that would clearly not let in enough light for plant growth. So with help from my brother inlaw Jack we cut out part of the northern and western metal wall cladding and replaced it with Laserlite sheeting (another polycarbonate product). That didn't seem to let in enough light either so the steel sheeted roof area over the growbeds was also replaced with Laserlite.
Just in case this lets in too much light in mid summer I made a retractable blind from 70% shadecloth and attached it to the roof joists so that if needed I can partially shade the area in the hottest part of the day. At this time of year the blind is folded out of the light.
I am still not sure if we are getting enough light onto the plants and I have some more Laserlite to convert more of the roof if needed.
The shed has 3 large roller doors and small louvre windows in the apex of the roof at each end so I hope that we will get enough air flow to prevent overheating in the summer.
I have taken to opening at least one of the roller doors when I feed the fish first thing in the morning and closing the door after the last feeding at night. The vague theory is that this way I am getting airflow and reducing the risk of fungus due to high humidity and still air. Time will tell if this theory is valid. I am assuming that the height of the growbeds off the ground will keep rats, rabbits and those big rabbits (Kangaroos) away from the lovely lush green stuff.
I also have a plan to make big hanging curtains, with shadecloth, for the door openings if needed to keep out grasshoppers if they become a problem later in the summer.

Power

The pumps are 240V AC and this is supplied via an inverter over the battery bank which takes 12v DC and changes it into 240v AC. (The inverter is not shown in the picture as I didn't have it when that pic was taken).


I decided to use 240V AC for a couple of reasons:-

1. I had already bought an inverter (on e-Bay) so that I could use 240V AC tools in the shed which is not directly connected to the house power supply. The shed contains a battery bank which was a cast off from the house some years ago and which is kept topped up by two 80watt Solarex PV Panels on the shed roof. The bank is twenty four 2Volt 560Ah batteries each of which weighs about 50kg. These batteries came out of a Telstra phone exchange and were part of a batch which included a bunch of duds- so I had to replace all them with new ones for the house supply- another saga in the life of an alternative energy enthusiast.

2. It has been difficult to find quality 12V sump/bilge pumps.

I have wired in a 240V AC outlet near the fish tank and this has the remote float switch plugged into it. This float switch bypasses the float switch on the new pump. The float switch is attached to a pole in the water and the levels at which the pump switches on and off are adjusted by changing the length of the tether on the float and the position of the ties on the pole.
It looks like the total power usage per day exceeds that generated by the panels so I have run a 240V line from the nearby pump house and have plugged a small battery charger into that line. This now trickle charges the battery bank and seems to be keeping up with the demand of the pump. The new pump should reduce the drain on the batteries significantly.
The pumping cycle now is pump on for about 8 minutes and then off for about 56 minutes. This gives about 22 cycles a day. Each cycle pumps about 750-800 litres a time so the total tank content is cycled through the growbeds about 4 to 5 times a day. In fact it is actually a bit more than that because the water is returning to the tank at the same time as the pump is moving it out. A quick experiment today suggests that the pump is actually moving about 10-15% more water with each cycle.

Plumbing

As you can see in some of the earlier pictures the plumbing is in 2 sections.
1. The water from the fish tank to the growbeds and
2. Return water to the fishtank.
The first bit is via a big sump pump which is on the bottom of the fish tank and is connected to the growbeds with 1 and a half inch (40mm) black agricultural polypipe. This is used because I had lots of the poly bits in stock as it is the same pipe we use for all the outdoor plumbing between dams, the bore and header tanks etc. The pump is in a filter sort of bag I had to make to prevent the fish from being sucked into the pump and mulched. Not a happy thought.
The return is via gravity and 90mm stormwater pipe.
The water was very muddy initially so I made a filter from a mop bucket with many holes in the bottom and about 15-20 layers of quilting batting from spotlight. This has taken most of the mud out over time. It also probably increases the aeration of the water which is a plus.

Each growbed has a gate valve on the input so that I can adjust the flows to even out the fill levels to individual growbeds. This took a fair while to fine tune and would have taken forever if I had used ball valves instead of "John valves". Each valve now has a cable tie to prevent accidental changes to the settings.
As the whole system runs on solar charged batteries it is very important to me that the pump is as efficient as possible.
So the gate valves are set so that the last growbed has a fully open valve and the others are closed just enough to ensure that they all fill at the same time.
The first pump is a big blue unit which is rated to pump about 15000 litres an hour to a head of about 2 metres using about 700 watts of power to do so.
The current pump uses only 250 watts to pump a rated 8-9000 litres an hour and actually only takes about a third longer to pump the same amount of water as the big one. This suggests to me that the big one is actually throttled back by friction in the delivery pipes. This came as a bit of a surprise as I thought short pipe runs and 40mm fittings would not be a real restriction.

Once the water gets to the growbeds it is distributed via a series of 25mm pipes with lots of holes in the bottom surface. This prevents water spray and hence evaporation and also limits algae growth on the top of the gravel. The return water from the beds is restricted by bits of 40mm PVC with just 2x 6mm holes in the lower section. This was just luck and means the return takes about an hour before the pump kicks in again.

Growbed construction

The growbeds are 1200l teampoly stock water troughs. They are about 2 metres in diameter and 400mm high.
These were chosen as similar to those used by Joel Malcolm. However I couldn't get a reasonable price for custom made steel troughs/tanks so I decided to buy poly ones. Poly will also not rust and is fairly easy to work with.
In retrospect I feel that round grow beds are not a good idea as they are hard to arrange in a limited space (I could only get 3 of the 4 I bought into the available space in the shed) and stands are complicated to build for a circular shape. AND it took 4 months for the manufacturer to complete the order!
The stands were complicated as the pictures show however they easily support the weight of gravel and water when full- estimated weight is probably over 2 tonnes per growbed when full.
I have put a layer of 19mm yellow tongue chipboard over the base then 25mm of polystyrene sheeting. I plan to also wrap the walls with polycell or aircell blanket material when we get closer to winter next year.
The stands were set on bricks so that they had a slight fall to the planned drain plug area and the drain holes cut unto the base. A normal laundry drain fitting was then screwed into place with a fair bit of silicon to ensure a waterproof join. Details will appear in the plumbing post.
The growbeds were then filled with gravel- Bungendore 10mm brown- selected for its smooth feel and average stone size of about 10mm. Really I just went to a sand and gravel place and handled all the potential media and selected one which felt comfortable to touch. Some people use blue metal but it felt to sharp to me.
Before the gravel went into the growbeds I had to decide if I should wash it. I did wash one cement mixer full but decided it would take too much water and also too much time. So unwashed it is. I thought that the flood and drain cycle would eventually wash out most of the silt etc. And it has although it took much longer than I expected. The system has been running now for just over 2 months and we can only now clearly see the fish on the bottom.
I feel that the silt and mud which is still visible in the growbeds will probably be good for the plants in the long term anyway so it was probably the right way to go. The only real problem was that I couldn't see the fish for the first couple of weeks and it is hard to know how they are going when they are not visible.

Initial construction - fish tank

It gets too cold here in the wintertime to maintain the fish I wanted to keep so I really need to build a super insulated glasshouse for this project . However I couldn't decide on how to do this despite many versions of plans in my head.
So I decided to modify one end of my big shed to accomodate a trial setup- ended up a bit big for a trial but I think it will work well enough to determine if the construction of a dedicated greenhouse will be worth the effort.
Without really giving the whole thing too much thought I decided to simply copy what has been show to work by Joel Malcolm in Perth. His system is outside but apart from that minor detail my system is fairly similar.
As stated elsewhere we are entirely solar powered (actually partly wind powered but that is really a small part of the total) and so the system had to be as energy efficient as possible.
So the tank and grow beds are, or will be, heavily insulated to conserve as much heat in the winter as possible.
I also had to minimise pump usage so the system is a flood and drain one where the pump runs for between 6 and 9 minutes in the hour and drains back via gravity. IE no sump pump.
I have recently changed the pump but I will leave the details of that to a separate post.
So the fish tank had to be below the level of the growbeds if a gravity system was going to work. It also needs to be well insulated so one really big hole was needed- 2500mm across and 1400mm deep.
Took me 4 days to dig the hole . Basically dug by hand- needed the jackhammer to break up the dirt and used the tractor bucket to move it outside. Not sorry to have finished that little job!
Then put 20-30mm of crusher dust in the bottom , leveled it off and added 25mm of expanded polystyrene over the bottom. Lowered the tank in, packed 30mm of expanded polystyrene around the edge and backfilled with more crusher dust.
The tank was then filled with water and left to sit while I tried to work out some way of heating the water. This part of the plan is still in thought/planning stage as the initial plans were thwarted by the fact that copper pipe in contact with the fish water releases copper which can be very bad for the fish. Continuing cold weather basically put the whole scheme on hold until it started to warm up in September.

First post and links to my threads elsewhere

A new blog just for the fun of it so that I can show off my latest passion.
Actually this is a reignited passion as I used to have LOTS of fish tanks when we lived in town.
Now live in the bush and have lots of room to indulge in experimental things.
Because we are entirely solar powered, in the grip of a fairly severe drought and always want to have as small a carbon footprint as possible the concept of Aquaponics has huge appeal.

It all started with an article in Organic Gardener (ing?) about this bloke, called Joel Malcolm, in Perth who apparently grew 60kg of Barramundi and several hundred kilograms of veggies in his backyard. I bought his excellent book , read it cover to cover several times, and started building a similar system.
Check out his web site:-
http://www.backyardaquaponics.com/
and the associated forum
http://www.backyardaquaponics.com/forum/
All sorts of good stuff to be found there. A bit of chaff to wade through sometimes but also a lot of really great informantion.
I have a thread here :-
http://www.backyardaquaponics.com/forum/viewtopic.php?t=1431&highlight=
Another useful site is
http://www.aquaponicshq.com/forums/index.php
my thread is
http://www.aquaponicshq.com/forums/showthread.php?t=17
This one doesn't have as much activity and a lot less chatter but also some really useful info.
Both site are Australian based so most of the info applies to us.

Part of my justification for this blog is that I post to both sites on an irregular basis and this might enable me to keep a more current series of progress pics and thoughts.
The posters on both forums(?) are usually a lots further advanced that I am and probably aren't going to be as excited as I was today to discover that my catfish really love mosquito wrigglers for example.

You might have gathered from the somewhat disjointed waffle above that this blog will be a somewhat haphazard affair- but isn't that what blogs are for?? More later.