Backyard Aquaponics
A place to discuss aquaponics

I believe I have achieved proof of concept with my small system as, although I am yet to harvest any fish, I have been able to successfully grow vegies so I have begun to plan my big system and I would like the forum members to tell me if it will work as the volume ratios will be unconventional.

In the interest of keeping costs down I am going to use what is available to me. This 30,000L aqualined rain water tank which is 2/3 under ground will be the fish tank and will hopefully be very temperature stable.



The 4,500L FT from my experimental system will be the sump and I will get 6 more of the round 1000L GBs I am already using (pictured below) to bring the GB volume up to 8000L.



This is the layout, I am hoping that I can make it chift pist using the 4500L tank as a sump and is why I am only using 8000L of GB (and to keep costs down). The gradiant of the land from the FT may not allow this.



Now I know the ratio of FT water to GB is way out of optimal so I guess I have two options:

1. Keep the FT full and stock to the numbers that can be supported by the GB volume.

Advantage: Greater water temp stability (maybe trout all year round) and safer for fish.
Disadvantage: fish waste nutrients will be dilute requiring higher water turnover to get the nutrients to the vegies or poor vegie growth

2. Keep FT volume at a level that is closer to what the GB volume will support

Advantage: Better vegie growth and less pumping required
Disadvantage: less margin for error on water quality, poorer temp control


What do you reckon, will it work?

Looking good simo, I think it will work and I would stress about the GB Ratio, I have 6000lt of water and 2000lt GB and manage that with the amount of fish I have, no drama's and have had 50 plus trout survive, around 150+ yabbies and a few other things like mussels and Pygmy Perch, I still doubt you will do Trout all year round, in my attempt I have found they can handle a day or so of water around 22 but can't handle continued temps, hot days and cool nights (around 14c) is great as water drops to 18 overnight, but warm nights and no cooling, you would also need a shit load of air to attempt to run trout all year, my system is under cover and yours will be outside which means GB's will be heating up the water, you will also need a mother pump to turn that amount of water over in an hour unless you go continuous flow, then you have the water heating all day, your system will work, but I doubt anyone North of me can grow trout all year unless in climate control environment which = $$$$

The volume/capacity of your bio-filtration... is, and always will be... the main limiting factor... with some limitations regarding water turnover/aeration....

Even if you were to drop the level in the tank... to match your growbed volume.... your stocking rate would still be effectively the same...

The greater volume just would mean greater stability, and margin for error....

So regardless... stock to your growbed filtration capacity...

Cool, thanks for the replies,

I put the stocking at 240 kg of fish or ~500 fish at various levels of maturity in 30,000L

Do you think with a larger volume of water the nutrients will be more dilute and therefore harder for the plants to utilise? Would I need to increase the water turn over to help the vegies and bacteria get to the nutrients?

or

Will there just be a slow start and once the levels of nutrients get high enough the veg will start growing

The latter... to some extent...

As AP is a recirculating system... the plants are exposed to the nutrients they required almost constantly... and will take what they need....

The nutrients might "appear" to be diluted in a large amount of water... but will probably still be sufficient for the actual plant needs regardless...

I think this is what happened in my current system, 200 tiny SP in 4,500L FT with only 2000L GB, slow start but plants are now growing well even though my readings are always zero

Just a thought, wouldn't it be difficult to fish out the fishes for harvest when the stocking levels are low compared to the tank size... I know it was hard to fish out the bigger sized fish in a 1000L without getting smaller ones ... in 30,000L I think it would take a while...

Duno if you mentioned this, but ensure those tanks are aqualined or otherwised protected.

That is true Ivan, the Ft is about 3 meters deep

But I wanted to keep costs down and the tank was already there.

You know what they say: "necessity is the mother of all invention"

Maybe I could use a fish stunner to catch the fish

http://www.amazing1.com/download/FISH80INSTR.pdf

I believe if you leave them in the water they will revive themselves after a short time

There are even plans to build you own

www.catfishstunner.com

I say pick a hot day and grab mask, snorkel, and long-handled net, and cool off for a bit.

Have a beer or three afterwards, not before.

And make sure you have a good way to get out as I hate to hear about unintentional AP fatalities. Seriously. Perhaps a boat ladder AND a friend. Heck, this could even be a great few minutes of entertainment at a party as you catch fish to cook up. But be safe: 3 meters of water is a killer.

Speaking of which: you will have a lid on to keep critters and kids out, right? Fish will die if there are too many rotting critters or kids in there...

How about rotary dividers in the tank made from plastic mesh?
pivot them off a decent pvc pipe in the centre of the tank and just bruhing the sides and you could grade the fish in the tank depending on the mesh size. and then when you go fishing the dividers will push the required lot of fish around to the opening in the cover and you can crowd them up with little stress.
John

Now that is a great idea, If I made the sections so they could be individually raised to the surface catching the fish would be easy.

I was more thinking of dividing the tank vertically into segments like an orange but with say three or four dividers that moved independently. that way you can give smaller fish a chance to keep out of the way of the larger ones and give each the amount of space they need and also push the dividers close together
to crowd the fish up when inspecting or catching them.
The vertical post in the centre that the dividers rotate around could also be the chift pickup.
John

Well sections to segregate different size fishes in each would help with ensuring that the smaller fishes get their feed... and also can be fed smaller pellets....