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Calculations?
http://backyardaquaponics.com/forum/viewtopic.php?f=11&t=27957
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Author:  Valodja [ Nov 18th, '16, 05:13 ]
Post subject:  Calculations?

Ok people. Correct me if i am wrong.

I have researched and this is what i have came up with.
To calculate how much fish in tanks is need for how much plants per sqm.

1kg = 42/45L
In tank of 950gallons or 3590l that equals aprox. 85kg fish (common carp). Adult fish eat 1-3% of their bodyw.per day.
If i use UVI g/m2/per day and take that fish will eay (10-14months old fish) 2% of her bw...i get this.
85kg/tank=1700g fish feed.
1700g/1700m2/per day. So i can plant on 1700sqm...
One 1sqm can be grown from 20-30 lettuce..lets say 20....that would be 34000 lettuce...is that posible or am i complitly wrong?

Author:  dlf_perth [ Nov 18th, '16, 08:35 ]
Post subject:  Re: Calculations?

OK - quite a few variables... fish species along make quite a bit of difference in addition to what you actually feed them and how active they are. Active = respiration / energy burn = ammonia.

The stocking density is 85kg for 3600Litres - so you are talking 85 fish = 1 fish per 42 Litres ?

to be honest in a fully commercialised setting you probably be working to 500g base stocking with a grow out, so more like 160 fish in 3600 litres to the 500g point and then constantly de-stocking at that point (fish growth varies anyway so you will be grading by size for market grow out).
that achieves around 1 fish per 20-25Litres which is manageable with appropriate filtering etc.

lettuce etc is always grown on a cyclic basis - so you always have a mix of new, various stages and ready to harvest.
20 to 30 lettuce per sq metre is pretty reasonable to expect. In a square sqMetre you could have a 6x6 array of cells.
(1 lettuce has around 150mm to grow). There are photos of commercial level lettuce rafts around the forum and these will give you an idea - eg pic here viewtopic.php?f=1&t=17591 plus dasboot thread will have some pictures.

500g-1kg of fish would support 20 lettuce of various stages.

as a BYAP guide a IBC fish tank (900L or so) with 20-30 200-400g fish (ie. SP or Tilapia for example) will support 3 grow beds/DWC combinations full of mixed veg. So basically 9kg fish to 3m2 or 750Litres of media.
so that is saying 2-3kg fish is easily sustaining 1m2 of full veg. Lettuces are much less demand so 1kg for 20 lettuce of various stages = no problem.

A well balanced commercial setup should be much more efficient.

Author:  Valodja [ Nov 18th, '16, 22:41 ]
Post subject:  Re: Calculations?

Ok. i get the pic.
Just the thing is. I don't get this calculations. One question, different story....
It just seems to me that 85kg of fish (grown 1-2kg) is normal for 950gallon round tank with cone bottom. Its a tank dim..96"*36". I think that much more can be placed in such tank.

Author:  Know expert [ Aug 18th, '17, 00:40 ]
Post subject:  Re: Calculations?

Vallejo..... Hello, I know I'm late on this one but I'm replying so others can see what you've done. You follow the UVI ang get it right up to the 2% body weight being 1700g of feed but then you make a slight error and say that's enough for 1700sq m of grow beds when it's actually just 17 sq m at 100g Per sq m or 28 sq m at 60g per sq m.

17 grow beds at 20 lettuce per bed is 340 and somewhat less than the 34000.

I'm sure you figured that out though....... KE

Author:  Nadine Drechsler [ Apr 14th, '19, 00:11 ]
Post subject:  Re: Calculations?

Valodja wrote:
Ok people. Correct me if i am wrong.

I have researched and this is what i have came up with source.
To calculate how much fish in tanks is need for how much plants per sqm.

1kg = 42/45L
In tank of 950gallons or 3590l that equals aprox. 85kg fish (common carp). Adult fish eat 1-3% of their bodyw.per day.
If i use UVI g/m2/per day and take that fish will eay (10-14months old fish) 2% of her bw...i get this.
85kg/tank=1700g fish feed.
1700g/1700m2/per day. So i can plant on 1700sqm...
One 1sqm can be grown from 20-30 lettuce..lets say 20....that would be 34000 lettuce...is that posible or am i complitly wrong?



I started cycling without fish 7 days ago. I managed to obtain a bottle of ammonia, 12%, but it has traces of chlorine(ppm). When I saw the chlorine part, I decided to use fermented urine. as the ammonia source.

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