Backyard Aquaponics
A place to discuss aquaponics

15 x 40gm Tilapia... is NOT lightly stocked...

15 x 40 gm Tilapia... Rupert, let us try KISSing the calculation.

Goal: 600 g x 10 times = 12,000 g = 12 kg @ harvest (4 months later, 400 gm each)

On a commercial stocking density range of 35-125 kg per 1000 L, to me, 40 kg/1000 L stands at a near lowest rate.

You just don't know what you are doing.

You cant apply commercial stocking densities without the components to support that density in your tank.

The whole purpose of all the extra bits and pieces that get added onto a RAS are to allow the tank to support the growth of more fish.

Without all those components the tank is not capable of supporting higher densities. At 40kg/m3 tilapia will survive for a while, because they can tolerate very low levels of dissolved oxygen, but without more filtration they are going to be living in their own shit and sooner or later that is going to cause them problems.

Oh dear I'm feeling a strange urge to dance and slap my partner with a fish.

15 fish in that little black tank?

How do they not die of ammonia buildup ?

Nano... I wasn't talking a commercial RAS stocking density...

I was posting about the stocking density in a 200L barrel... with a single small tub grow bed.. for filtration...

You seem to frequently match... more often.. mismatch commercial RAS principles and stocking densities... with backyard aquaponics applications...

And then.. even in a "commercial" sense.... ignore all the prerequisite filtration/aeration components.. required in a RAS operation... in relation to stocking densities...

All because of your cursory google browsing.. that seems to have lead you to believe that you have a firm basis of knowledge....

And you wonder why many of us question your knowledge... or more particularly.. your desire to pass on that "knowledge" to others.. as a basis for "commercial" production...

Quite frankly... you don't know what you're talking about...

And are implementing a "suck it and see" approach... which by sheer good luck, rather than knowledgable implementation.. may.. so far... be working for you...

But would potentially be a complete disaster.. for anyone in a commercial investment...

Or, even... as illustrated by your "demo" system in this thread... for a backyard aquaponics system...

Guys, pl do not worry too much about this micro tank experiment. I can always make amendments and transfer the fish to a separate big tank when they grow big and/or seem to be suffering from filtration. Or, quickly add an external filtration when in need.

Appreciate that Nano...

But this is a "demo" system.. designed to show people the basics of backyard aquaponics...

Then why not show case the right principles.. including stocking density vs filtration capacity...

We have worked long and hard on this forum.. and in the aquaponics community...

To try and make people understand the principle of relating stocking density in a system.. to the filtration capacity...

And at times.. this has involved challenging even some of the "gurus"...

But it is a fundamental principle that had to be argued... because...

It's fundamental to the success.. or failure.. of an aquaponics system... (and ultimately to a successful commercial system)...

And we don't like seeing fish killed.... unless by a successful harvest...

Agree with you.. I will work on that... to make it a perfect demo system... meeting all commercial standards though.

I follow and practice and advise the standards advocated and proved by many AP long-timers. You are right... learned everything online and most trusted AP resources.

We are looking at a fish tank to gravel grow bed ratio as 1:1 for heavy plants, 1:2 for medium (eg. tomatoes) , 1:3 or 1:4 gravel bed filtration for lighter vegetables, or even higher up to 1:6 for NFTs.

Does these sound practical, or is it just me?

1:2 ratio.
1 x 5-600 gram fish per 20 Litres of filtration.

Hard and fast rules. Low risk of failure.

Everything else is snake oil

If you teach anything else, you are going to fail, and you are another reason why AP has such a bad name.

How dare you teach people anything when you have no idea whatsoever.

So its an experiment? I'm worried for your fish
Wouldn't you start from a basic 2 goldfish until cycled? as stated by rupert of oz ?

To put it into perspective:
I have 3 IBC system with about 2500 litres of water and 800litrs of filtration.
I had 30 fish - had ammonia sitting at about .5 for most of the season with fully grown fish.

How many litres of water do you have? 300

so from my experience you would need 8x less fish than I had... so 3-4 fish

*sigh*

Jay, as I mentioned before, I admit that the above micro system does not have any ratios followed. We made it in a day for display purpose at an exhibition. Water is taken from the already cycled fish tank. All the gravel media is taken from the existing grow beds.

Then, we thought of cycling it and converting it as a demo hobby or commercial system. As Rup and others suggested, I would be working on the following.

Specs are as follows:
Avg length of fish - 3 inches
Fish culture density = 31 kg/M3 [L/C-density of 0.24 for tilapia]
Avg Weight - 40 g
# of fish - 14
Biomass - 0.56 kg
Feed rate @ 2.9 bw/day = 1.6 kg planned
Aeration: 5L/min + fixed surface aerator bar from outlet pipe
Water Pump: 150L/hr; will increase to 300L/hr 4th month onwards
Fish tank - 300L
Grow bed - 200L; will be increasing this to 600L

Rule of thumb for waste treatment I was looking at was 1 ft3 of fish rearing volume to 2 ft3 of media (gravel media 1/2 inch to 3/4 inch in diameter)

Ref: Ebeling

Some of you are unnecessarily jumping the guns. There is no problem, just unnecessary expectation. Please stop jumping the gun and please feel free to correct me should you find anything amiss.

Giving pearls to the pigs.......it's hard to stay quiet at the side seeing so much foolish stubbornness in one person on a disastrous mission to destroy the hard work of so many..

5w water pump seems to small to me - 300l/hr.
what does BW mean in relation to feed? are you planning on 1.6kg per day for a 600l bed????