Jimbo's new system

[Jimbo]

Hi Folks,
I am now at the almost ready for gravel washing- about 5 or 6 tonnes of the stuff- plan on using a big cement mixer on the back of my tractor.
The system will comprise a 4500 litre fish tank- sunk into the ground and insulated with about 30mm of polystyrene sheeting and 3x 1200 litre grow beds on steel frames. The grow beds will sit on chipboard and polystyrene foam and will feed back into the fish tank by gravity. The system is very like Joel Malcolm's original big system with the variation that return water is not pumped. At this stage I think I will probably have Tandanus tandanus (eel tailed) catfish as they 1 . available and 2. likely to survive the low temperatures we get here , near Canberra. The fish tank has been full of water for 5 or 6 days and seems to be stable at 11 C. The system will be flood and drain using a 15000 litre per hour sump pump and remote float switch. Planning on pumping for about 7 or 8 minutes per hour- rest of the time draining.
The pictures show the lid still on the fish tank- this will be removed when I have fish and have made another cover to keep miscellaneous beasties out and the fish in.

[GaryD]

Hi Jimbo,

Your system is developing nicely. I particularly like the grow bed stands.

My only concern is whether you have enough "spokes" in the grow bed stand. Grow beds of that size will be very heavy when filled with gravel and I'm wondering if the grow bed will be adequately supported across the base.

Gary

[Murray]

Hi Jimbo,
Perhaps a sheet of 12mm ply or similar on the stands to help support the bottom of the grow beds. You have possibly already thought of something like that.
The grow beds are a good size, but in the pix they look a bit "floppy" but I am sure they will work fine once on the stands and supported well.
My gravel supplier tells me that most gravels weigh about 1.75 times that of water. I don't know how exact that info is, but I guess it is very close.
A big grow bed can end up weighing tonnes. Unless the base of the grow bed is supported well there is a potential disaster waiting to happen. (with any type of grow bed)
Muzza

[Jimbo]

Murray has guessed correctly- I am going to put a layer of 19mm yellow tongue exterior chipboard, the stuff they use for flooring in new building, onto the stands first , then 25mm of polystyrene then the grow beds. I also want to insulate the outer wall of the grow beds and believe I can get pink batts , or similar, with an a sisalation like outer layer. If I can get these in rolls it will be just wrapped around the outside.

[RupertofOZ]

Chipboard can deterioate over time if it gets wet Jim.... do you plan to seal it at all????

The pink bat insulation idea has worked well for others

[Jimbo]

Rupert,
this is the fancy waterproof stuff they use for flooring in building- I have seen it exposed to the weather for months without problem.
However I guess it is better to be sure than sorry- I might seal it with something to be sure to be sure. Problem is the sealant will have to be inert just in case any gets near the fish.
Jim

Chipboard can deterioate over time if it gets wet Jim.... do you plan to seal it at all????

The pink bat insulation idea has worked well for others

[RupertofOZ]

Was thinking mainly about any exposed/cut edges that might get wet over time, or any water that might get trapped between the chipboard and the polystyrene sheet.

Good point to all readers regarding the use of sealants that are non toxic to fish.

[Jimbo]

It is quite a while since I have posted anything to this thread so an update is in order.
The main change to date is the substitution of polycarbonate for the cladding on the front and side walls ie northern and western walls, of the shed. About 1800mm high and total of about 10 meters of wall. I have now decided that that will not allow in enough light so I am going to put another 3 trays of clear polycarbonate into the roof- already had one tray and it looked fairly bright but almost certainly not bright enough.
Basically I have done very little as far the system is concerned as it is so cold here that the water in the tank is at about 8 degrees. Very little variation in the water temp despite the shed temps fluctuating between 21 and minus 1.
I have been planning some sort of heater for the water- basically an old solar hot water panel from a mates roof. I don't want to let the water from the fish tank into contact with the fish so a heat exchanger will be needed- still working on that idea. (Further thoughts about that on my other thread http://www.aquaponicshq.com/forums/showthread.php?p=1370#post1370
I have also been reading the threads which discuss washing or not washing the gravel and as I would be looking at about 5 or 6 tonnes of gravel I think I will try the non washing method with some sort of filter at the return point. I used to use a type of matting used in quilt making when I had fish tanks- very easy to just throw away the top layer so that will probably be the way to go.
I wonder if any of the other members of this forum know the name of an insulation product I was shown a month or so ago. It looks a lot like bubble wrap but a lot heavier plastic which is white. And it has an outer layer of an alfoil type material. About 1 cm thick and comes in rolls. It would be ideal to wrap around my grow beds. I thought it was called polycel or something like that but I can't find anything by that name.

[GaryD]

Hi Jimbo,

Here's some stuff on polycell......http://www.abldistribution.com.au/polycell_ideas.htm .....and here's their Australian distribution details....http://www.polycellpkg.com/contact.asp

On the issue of washing gravel, I'd consider using blue metal gravel. Blue metal gravel dust is full of goodies......like the rock dust that people buy to spread on their gardens.

I filled my gravel grow beds with it, filled my tank with rainwater and set a pump going. The dust all washed off of the gravel and went into the tank. The ph was 9.0

We pumped the tank out (onto the garden) and refilled the tank with rainwater and the pH dropped to 8.0. We added 200 litres of water from my other system and a litre of lemon juice and the pH dropped to 7.2.

This was a painless way to wash gravel.

You can use drainage gravel but that will be full of sand and clay and it will take a lot of work to clean it up. Some people don't wash their gravel but they probably shorten their pump life somewhat.

Gary

[Jimbo]

Thanks Gary, that is the stuff I saw. I almost had the name right- shame I didn't think to add another "l" to the search term.
And I have already got my gravel- bought it months ago- all 6 cubic metres -a truck load.
Called Bungendore brown 10mm- nice smoothish stones from about 5 to 15mm in diameter. Picked it because it felt nice in the hand and not rough or sharp. I washed one large cement mixer load and it took several fills of water before it was looking cleanish. I guess I have plenty of time before the weather is warm enough to add fish so I might just get the system into gravel washing mode in situ.

[redleg]

Hi Folks
i have seen air-lift made very simply and shift a lot
of water. This could rinse gravel without any wear on pumps.
verticle pvc pipe +elbow at the top.drill top of elbow for air tube.
insert air tube down from top elbow down to close to the bottom
of pipe.(angle cut at bottom).pump air down air tube to circulate water.
do you think this would clean gravel?
insulation is air-cell

[Jimbo]

Another update with pictures.
The system is now up and pumping.
I chose not to wash the gravel which might have been a mistake as the water is quite muddy. With a bit of luck the filter box I have on the return water will eventually take out most of the dirt.
Flood cycle is moving about 1500 litres of water in 6 minutes to the grow beds which then drain for just over an hour back into the tank.
This afternoon I introduced the washings from a big sponge filter from one of my other fish tanks into the big tank to initiate the cycling of the system.
Next job- chuck in some prawns to get the ammonia levels up.
Gary- how many prawns would you suggest for 4000 litres of fish tank? Complete with shells etc? and just into the water or suspended in a bag near the pump?
I am under pressure from better half to "get some peas in" and will probably do so long before it is safe for fish. So Seasol to the rescue I reckon.
The pics show the modified shed, the fish tank with muddy water and filter and overall views of grow bed setup.
At this stage I have put the plans for a heat exchanger on hold

[Murray]

Looks great Jimbo. I do not wash my gravel. It settles completely in about two weeks. The sediment winds up on the bottom of the grow beds. Helps make a really good grow bed.
I gave up washing the gravel after the first grow bed. I reckon it wastes too much water.

[GaryD]

Hi Jimbo,

The water will clear up soon enough.

I used blue metal which, rather than being full of clay and sand, contains rock dust which causes a high pH (which nitrifying bacteria favour) and which contains a whole heap of nutrients which plants quite like.

For those who elect to use blue metal, the high pH will be no issue if they are going to cycle their system without fish......and it will settle down to a more acceptable level once they're ready to add fish.

Transferring the gunk out of your aquarium filters will help to kickstart things.

You can use any source of nitrogen.....prawns, fish meat, fish pellets. Try about 500g to start with......and then begin to test your ammonia levels daily. You should be aiming to get the levels up to 5. Once they achieve this and return to zero, your system is cycling.

You can use a little Seasol, to provide nutrients for any plants that you may have in your grow beds while you're waiting for your system to cycle.

Some people are critical of nitrogen dosing (aka fishless cycling) based on the possibility of introducing diseases into your system. They'd rather use goldfish or feeder fish.

Personally, I'd rather use anything but goldfish. In my view, you stand a greater chance of contracting a disease like ICH or fin rot from fish you've bought from a pet shop, than you will from prawns or fish meat.

Gary

[Jimbo]

Thanks Gary- better half says she has some frozen fish in the freezer which is well past its use by date- big chunk going into the fish tank today.
I had already bought the gravel-based on how it felt in the hand - ie not sharp and easy to move about. Also has lots of irregular surfaces which should mean greater surface area for the biofilm.
I am very much in agreement re fishless cycling of the system- the fewer sources of potential disease the better.

[skygazer]

[QUOTE=Jimbo;35]
3x 1200 litre grow beds on steel frames. QUOTE]

hi jimbo,
where did you get the grow beds and how much did they cost?

[Jimbo]

The growbeds are by Team poly- standard 1200l stock water troughs.
I bought them from their agent in Queanbeyan- took AGES to come- about 4 months.
http://www.teampoly.com.au/Pages/main_products_trough.html
Cost about $460 each- that included brass fittings .
If I had to do it again I would try and get rectangular beds as they are much easier to setup in a rectangular area. Big benefit of the one I have is that they are big so I guess it's swings and roundabouts.