Backyard Aquaponics
A place to discuss aquaponics

I was talking to a guy at the pub and he works with 120 slightly disabled people and they have just stocked their dam with trout and are looking to do vegetables as well. can you use aquaponics on such a large scale ? or will it change dramaticly the eco system of the dam? some imput would be nice as i would dearly like to help a worthy cause

Monia [the fish farm near you ]sold a market gardner 30000 fish to put in his dam so he could irrigate his market garden i dont know how it went

How big is the dam, and how many fish did they put in?
I hope he has extra airation. I know a bloke in the southern Adelaide Hills who lost a whole lot of trout in his dam because the weather got a bit warmer and he didn't have any air or splashiing in the dam.

i didn't ask but thanksfor the reminder

Must have been a bloody big dam....

Depends on what model of aquaculture they're employing... if the dam was stock as an extensive system... i.e ... with a stocking density that can be maintained by natural feed sources... and self regulation of the fish stock population...

Then it will be essentially a "balanced" eco-system, with aquatic plants, reeds etc and water repalcement from rain.... essentially utilising and regulating the nutrient wastes...

If it's run as an intensive operation, with supplementary pellet feeds and aeration... then certainly the nutrients could be utilised for vegetable production... and they'd need to be...

Otherwise nature will force them into full "bloom management" aquaculture...

The size of the operation (if intensive) may also result in the requirement for licencing... and would certainly attract the attention of the EPA in terms of utilising the nutrient wastes on land based agri-crops...

Creating Aquaponics on such a large scale could be done, however, it will probably have more chance of success if planned out from a stage before adding extra fish. Starting The planning for Aquaponics after you add the fish is kinda "putting the cart before the horse" so to speak.

However looking back you don't say how much fish they stocked or how big the dam is.

To make a balanced AP system you need to figure all three parts.
1-fish
2-plants
3-filtration (bacteria and solids)

And the plumbing and such to make them work. Keeping in mind that all three parts usually put extra oxygen demand on the water so added aeration will help all three.

I fear many people out there who have only heard of Aquaponics in passing, only caught the part of the description that says it's fish crossed with hydroponics (as in they see fish and plants and no one stressed the extreme importance of the unseen part of the system which is the bio-filter bacteria and solids filtration.)

I agree with TCL, you can't go beyond what the bacteria can handle or you start running into water quality issues that eventually affect your fish. You are then stuck with external biofiltration or water changes. There are formulas, on this site, for calculating the bacteria load on rafts and in various medias.

You might want to check into PAS (passive aquaculure system) ponds for some additional ideas.

Sorry, just want to clarify- PAS stands for Partitioned Aquaculture Systems.

http://aquanic.org/publicat/usda_rac/ef ... 4500fs.pdf

will need to chat with them a little further, just from my understanding the whole thing is to get the people playing with fish and vegies for themselves like i have tried to do the kids to get them to eat vegies

My neighbour has a dam that holds about 200,000 to 600,000L at different times of the year, he has seen my AP system but as nothing has grown yet he remains sceptical.

We have had a discussion about aquaculture using his dam water and come up with the following idea:

Wind mill (with possible powered pump back up) continuously pumps water to a large tank in a protected area where Marron are grown and then FT water drains passively back to dam where existing aquatic/semi aquatic plants and algae remove nutrients. Essentially the existing dam ecosystem is a large biofilter.

No vegies as the large dam water volume would need a very high nutrient content and therefore stocking density to get good plant growth and then fish/marron would be harder to keep alive.

Why not just throw marron in the dam? Because they are easier to keep alive in a tank where they are protected from birds and the environment can be controlled (temp, DO etc...) plus better feeding efficiency as you know where your marron are and how much they are eating.

Why not just do an AP setup? Like I said he is a sceptic and has no shortage of water and grows fantastic vegies in dirt so he can't see why he would put so much investment and effort into AP, but once he sees the phenomenal plant growth I hope to achieve and he eats some fish I am sure we will be converting that marron tank into an AP system quick smart.

totally agree. to be able to use such a natural source and with the understanding that we will not always have water you can't go wrong