Backyard Aquaponics
A place to discuss aquaponics

how many gallons is that?

160 gallons. You could do about 1200 liters of growbed volume. I guess i shoulda just multiplied liters times two

LOL MF! What did you do? covert L to G times by two then convert back ?

Roy, the back yard aquaponics manual wouild be an invaluable resource for you adn your school, either PM earthbound or follow the links on the main www.backyardaquaponics.com website.

"I wonder how many plants you would need for a 600Ltr water tank?"

Assumptions:
--Grow Bed is 12in/300mm deep
--Tank to Bed ratio is 1:1 by volume (If you want to go up to 1:2, you can do the math.)

Therefore, a 3foot x 7 foot would do it (ok, call it 1meter x 2 meters). (Do I have to show my work, teacher? Do you want it in English or metric system? So, like, there are 231 cubic inches to the gallon, and a lettuce plant needs 16 square inches of space.... )

Using the ever-popular lettuce plant, I plant my dirt garden at 4 plants to the square foot (Yes really, 16 square inches each. See here: http://www.squarefootgardening.com/)

So you would need 84 lettuce plants to fully plant your bed.
Or 189 bean plants. If Steve will 'let' you plant beans.

Either way, we're talking one or two packets of seeds.

--Janet.

But doesnt that also depend on the amount of fish?

What is the ratios needed for:

Size of tank vs number of fish?
Size of tank vs Amount of growbed (just answered)
Number of fish vs number of plants supported
And where do i find the space requiredments for all the plants?

Im getting our Library to order Joel Malcoms book and DVD... but that might take a while.

Also been told that I have to have the budget in by next Friday... I have got 1 week.

If you are experienced, fish:tank:bed at 1lb:2gal:4gal gives you the highest density of fish you should reasonably try. The metric folks are using a similar round-number formula, but I can't remember it at the moment. There's been big discussion about this, and how quickly a newbie to fish culture will kill their fish if they try the high densities. Someone more experienced at AP should advise you. Although I have dirt-gardened and raised fish for years, the combo is new to me. I am cycling my first AP setup.

My feeling is that there is not a precise formula for fish:plants. Maybe one could work out something for fish-food:plants, but in truth, you will have to balance as you go. Test the water. If the nitrates are too high, add plants, eat fish or reduce fish food. If too low, eat plants or add fish or feed fish more.

The spacing I offered above is based on dirt-gardening with Square Foot Gardening. It allows solid leaf-canopy, yet allows plants to mature reasonably. Again, you will have to experiment, or perhaps someone with a functioning system can advise.

Hi MCPHRO, I guess the reason your not finding exact figures on these questions is because it's difficult to give exact figures. There is no one right answer for aquaponics, and systems vary incredibly.

As an example, I have many different systems, here is one http://backyardaquaponics.com/images/system1.jpg As you can see, huge fish tank, with a tiny growbed, this system can support about 12-15kg of fish and the growbed is very productive.. But then I also have a much larger system http://backyardaquaponics.com/images/system3.jpg and a few other systems of different shapes and sizes.. In the large system I have about 40kg of fish, yet the fish tank is about half the size of the first one, but there are a lot more growbeds..

I guess the point I'm trying to get accross is that there really is no right and wrong answers, there are no exact figures for fish tank size vs growbed vs plant.. There are recommendations for figures that have worked for others, but often every circumstance is different. The link to the first picture I gave you could have a much smaller fish tank for the fish that are in the system, but then larger volume of water means a more stable system. And the growbed is only tiny compared with the fish tank, but it's all I could fit there at the time..

What are you able to get in the way of materials in your area? That is often a determining factor in the design of a system, and what is your budget.. I would see these as two of the most important factors in a design.. The fish stocking and plant growing are something that you can work out later..

I know this doesn't really help a great deal....

Agree with all, thing to remember is that AP takes the fish to water equation one step further and includes fish.

Easiest way is to use the given ratios but keeping in mind that it is the smallest part of the system that will govern everything.

For example you could have a 10,000L tank and 20,000L of grow beds, but you will only be able to plant out the number of litres of the grow beds that correspond to your fish numbers.......otherwise the system is in the negative for nutrients. Follow?

I always advocate going as big as you can (Jaymie took this advice verbatim, funny girl ) as it gives your fish tank temperature and chemical stability, just match your grow bed to the fish stocking densities as the tank is irrelevant if its way above the ratio.

Example: max rate consensus is 60kg of fish TO 1000L water TO 2000L grow bed. So if you decide to go 2000 lt fishtank, but 1000l growbed, then you could reasonably expect to stock a maximum of 30kg of (grown) fish. See how growbed now becomes the limiting factor?

We should probably start a sticky collating all this info.

Steve

No, i think i get it. As it also depends on the type of fish you have in your system, the number of fish, the strength of the feed you are giving them, how much waste the fish are producing leading to how much has to be taken out of the tank on a reqular basis to make sure the fish stay healthy.

And the amount you take out determines how big your growbeds are etc.

Also another factor would be: As plants get bigger, so does the amount of nutrients they require.

Ive also got to look at the sapce ive got available vs what im allowed. The HOD amd another senior teacher also said to start with a "pilot" project and build up etc.

So i was thinking of 1 or 2 growbeds with 1 Fishtank in a 3 or 4 * 3 or 4 meters squared area.

I was also thinking of having Barra AND Redclaw, seperated of course, just for the variety.

There is a Redclaw farm in Biloela and the waterboard in Gladstone. If I can work it so each loans us animals and we give the animals back when their larger - this should fix our... ethical problem I hope.

correct! and the beauty is the fish gett bigger too, with an increase in feed and hence nutrients, nice, huh?

How much solid waste do fish produce. If you had a worm farm with worms that ate their own body weight per day, then even if you had 500g - 1 kg of worms, you would need that weight in fish poo per day. I dont suppose they produce that much now do they? But how much do they produce?

And would it be worth using worms to turn it to good compost anyway. Would you just not bother and use the bacteria in the growbeds.

Id like a worm farm as part of the system if i could for the educational value. Even if it was supplimented by scraps from school.

Use the worms to process food scraps. if you have surplus worms when they breed then feed them to the fish. The solid fish waste will breakdown and mineralise of its own accord in the gravel beds and provide phosphorous and potassium to the system.

Chuck a few worms in the beds if you want, an outside system will attract them anyway, i know joel has found worms in his gravel, as did i a few weeks ago when i pulled my syhstem down for a re-design.

Steve

I see, with a population of 1000 - 1100 students, we have a ready supply of material for a worm farm, and the worm farm supplies the aquaponic farm. Thats not bad, thats the sort of stuff that makes the 4pm kids shows LOL.

IF we had a 600lt tank, how many fingerlings do you think we would need and how many worms to feed them.

BTW - I dont know, how many times a day do you feed fish? Ive kept fish in tanks when i was a kid, but this is different?

Different in the sense that i find people are told to feed less rather than more in an aquarium, even fish the fish want more, becasue at the end of the day (month ) the quicker the nitrate build up the more often you need to do partial water changes. Not so in AP

Rough maximum in a 600 lt tank with 1200 ltrs of growbeds is 36 kgs fish

so if you want to grow each barra to 500 gms before release then stock it with 70 barra, and so on.

Steve

Of course that is a maximum stocking level.... For a school system that won't have attendance on weekend etc, I'd be thinking that almost half that amount would be advisable, perhaps between 35 and 50 fish.. It would be a lot more stable then, plant growth may not be as impressivebut it would still be good.

Does anyone have any information about worms and their composition? I know that pellet feed has been formulated with additions of vitamins and minerals for fish health, I just wonder how complete a diet of purely worms would be..

More research required......