Backyard Aquaponics
A place to discuss aquaponics

Hello all,

my name is Dimitris, I was born in 1972.
I am a computer science teacher in Santorini, Greece.

I believe in aquaponics, but I do not think it is as easy as "follow those guidelines and it will work".
The skill to make things work always comes after hard work.

I want to learn aquaponics by building a medium-size system first, say with 100-200 kg of fish.
This will depend on standardized sizes of hardware used (plastic tanks, wooden planks, electric pump, etc) and I am not exactly certain what it would be. But I do not wish to make something too small.

For me its not only about eating vegetables or fish. It is about acquiring the knowledge about a promising technique for the future. Who knows, perhaps one day my kid will live off that! (I certainly wish it succeeds that much!)

My topmost priority in this and everything I do is "reliability". I am not the risky type. I always prefer something that will work 90% of the time over something that will produce twice as much but might fail.

I like the floating raft approach, because I find gravel or other medium to be expensive and heavy. Then again, perhaps I am wrong.

I have many intermediate questions that I try to answer by studying. I will try not to bother the forum with things already said. That said, if anyone can spare 20 minutes to answer a few basic questions I have, please PM me and I will get back to you.

Congratulations to everybody for this effort. It is what our world needs.

Cheers,
Dimitris
Greece

Hi Dimitris.

Welcome to the forum.

I can probably help you with questions, ask away on here. With the DWC vs media bed, I'd recommend beginners start on Media beds, its far easier, with less things that can go wrong. It's just a matter of pumping the fish tank into the sump to the media bed and draining it to the fish tank (or a few other combinations of this).

If you go the DWC route, you'll need to setup filters, mineralisation tanks, and spend extra money on air pumps. My media beds still outgrow my dwc beds (although after 6 months, the DWC is starting to catch up).

However, if you're serious about it, and have the same attitude as me when somebody tells me not to do something, Ryan's backporch system is a good one to study:
viewtopic.php?f=18&t=8754&p=256897#p256808

Hello again!

Wow I saw your projects, you have put a lot of work in this! Well done!

Ok those are my questions:

1. First of all I can not understand why the growbeds volume must be 2x times the fish tank volume?
This creates the need for a sump tank. Why not have GB volume = FT volume and simply put less fish in the tank and pump it every 2 hours instead of 1 hour ? This way we skip the need for a sump tank.

2. The other question *was* wether a fish tank can be made from some wooden frame, inside of which we place some synthetic fabric. I plan to use the fabric that inflatable boats are made of (there are two kinds, PVC which is cheaper and Hypalon Neopren which is an expensive "layered" fabric which is practically undead (it has layers for UV protection, etc etc). From what I saw, this is how you did it too, so I guess the answer is yes ? Please verify.

3. Another question is wether it can be done outdoors. There will be shadow over the whole arrangement. In Greece we often use a green "net" that stops about 50% of the sun. This is very commonly used over gardens to protect the plants from drying too much and reduce the water needs. So I will put one of those over the whole thing. And inside the fish pond I will have something floating to block the sun to the fish. But some sun and insects etc *will* eventually go through. Is this of critical importance ?

4. And the last question is how much do the fish eat and how much does it cost ? For example suppose I have 100 kg of fish (that would be about 220 pounds). How much food do they require daily and how much will this cost ?

I am serious about it but trying to figure out wether I can build it myself with minimal cost but without compromises in quality.

Thanks a lot in advance, you are really helping me here,

Dimitris

PS: Oh, I forgot to add that your note about the medium approach is noted and I will probably do like you suggest. I did not know that the floating approach was harder. Thanks for this as well

The pumping speed is to remove ammonia & increase oxygen to the water, and to keep the water mixed up. It doesn't need to be followed exactly, but it's a rule of thumb that has been followed sucessfully by many aquaponics people, and many more aquaculture people.

Remember, the plants are the side product of looking after the fish. Happy fish, happy plants.

The sump for me is to stop the fish tank running dry if something goes wrong. So if a pipe breaks while your at work, you won't come home to fish flapping on the bottom of the fish tank. And it makes it easier to top up water, or to know how how much you're going through. It also reduces stress on the fish with their tank running out of water.

But if your fishtank is huge, you won't need to worry about it.



The fish tank can be anything really, as long as it holds water. And make sure your plastic is potable water safe, or drinking water/fish water safe. Some plastic liners contain chemicals that make the plastic flexible, these can be bad for you, but it'd debatable how bad.

I have issues with the plastic, and creating a good seal against the fish tank, but that was probably my fault.



In your fish tank, if the sun gets through, it will bloom with algae. Algae will sap nutrients and oxygen from your fishtank. You want to avoid it, so try to keep the sunlight out of your fishtank.

With the light on the growbeds, I'm in Adelaide Australia, and we have a very similar climate. During summer, we had a 44C heatwave that lasted a week. In my growbeds, my tomatoes didn't even wilt (I felt like I was about to die though), they've got a constant supply of water, and they thrived, while my neigbours plants died.

However, many people on here use shade cloth, and it might make you go through less water in your system.

And the fish will happily eat your insects.



I'm imagining fish food will cost different amounts in different areas of the world, I get my food from here:
http://www.bignutrition.com.au/shop/

Per day, you should feed them 2% of their body weight, which should work out to 2kg per day for 100kg worth of fish. But they don't start out eating that much, they start out little, and get bigger over time. I bough a 4kg tub (about $25AUD) of feed 5 months ago, and I'm still using it up, but my fishies are little.

Another suggestion, beds can be added over time, it doesn't need to be done at once. Just design your system with expansion in mind, and you should be fine. And you'll always be able to build it cheaper yourself. Just remember the grow beds will be heavy, I'd suggest to over engineer, so make everything stronger than it needs to be.

It doesn't have to be but if it isn't then you must compensate in design or operation in some way as you have suggested.

Then best place to put your pump is in the sump. Other configurations will work, and even work well, but the pump in the sump is best. If you do as you suggest then essentially your are wasting half your FT. Nothing wrong with that per say but it doesn't necessarily save much if anything.


Lots of people do this but don't go for the PVC option. Do a search lots of discussion on this.


It can but depends on your climate how well it will work. Really what you put your system in is a separate decision, whether it be a paddock, poly tunnel or climate controlled GH. Depends on what you are trying to do and the climate that you plan to do it with or against.


You may need to do this or you might not. Shade can be a good thing but it can also reduce productivity. Better than green shadecloth is a reflective screen. More expensive but a lot better.

Thanks, guys.

I calculated the cost of gravel needed, and it seems prohibitive to use for a large scale.

For example, for a large plant of 3000 kg of fish, the gravel needed would cost 75000 Euros !!!
(riverbed gravel of size 10-20mm costs 4.80 euros per 16 liters/25kg).

(currently I am designing for 100 kg of fish, but it *should* be upwards scalable)

As far as I have found out, clay pellets are even more expensive.

So although I *could* use gravel for a small 100 kg installation, I do not think I should because I would be researching a method that I can not apply in large scale.

I suppose this is a disadvantage of the media method.


Another advantage of the "floating" method is that you can "move" the plants on a production line from start (small-lings) to finish (harvest).

***
So I was thinking perhaps of a hybrid version = have some "floating box" of dow foam but put gravel in it. It will sink partially. I could test it standalone on my backyard, before actually building the whole thing. How does it sound ?
***

Gravel is normally cheap but it might not be because of your location.

Are you on an Island?

I'd strongly recommend getting a medium size system up and running smoothly before starting to think about a system that can hold 3000kg worth of fish. A lot of people have lost a lot of money getting caught up in the hype.

However, some light reading for you:
http://www.uvi.edu/files/documents/Rese ... System.pdf

Certainly I agree, this is why I am making a 100 kg system first.

This will help me determine the various needs (area, electricity, materials, labor, etc) for the large one as well.

But my ambition is to design something that is scalable. For example if a 100 kg system requires 20 hours of work per week to maintain, this would not be scalable to 3000 kg because I would need too many people to work there for it to be economically viable.


Yes I am in an island. I will look into the price for gravel again, perhaps the ones I found are for "floor mosaic" artwork (they are round pebbles specifically made from a machine to look like riverbed pebbles). Perhaps there are cheaper options.

In Greece it is strictly prohibited to collect stones, pebbles or sand from beaches. One could end up in jail for this. So I can not collect those myself.

Another question that comes to mind is this:

When we say the system can hold 100 kg of fish, the yearly produce will be about 2 times this, right ?

I mean usually the fish grow within 5-6 months to an edible size, right ?

EDIT: by edible size I mean less than 1 lb, say 0.8 lb (300-350 gr)

Yes you are right, its about 24 Euro per cubic meter, thats much cheaper.

I cannot edit the message above to correct it, unfortunately.

Thanks,

Hi Dimitri did you get your system up and running ? Imnalso interested in starting an appointment system on the island of Crete