Backyard Aquaponics
A place to discuss aquaponics

Hi!

So a total fingerling (like what I did there?!) when it comes to aquaponics... We have just bought an old IBC tank and are hoping to set it up as an aquaponics system for 40-50 fish.

So much we need to learn! But very excited about this new project.

Welcome to BYAP

What sort of fish are you thinking about putting in your IBC? 50 might be a bit crowded for one IBC for fish you want to grow to plate size, at least for your first go at it (or for a fingerling, if you prefer ). It is best to start with a bit lower fish density, and with your next harvest you can go higher, once you've got the feel about how your system behaves.
You'll be needing to set up some grow beds too, did you have some more IBCs to use for them?


If you havent already done so, a read though the IBC of Aquaponics, linked at the top of the page is worthwhile.

Hi Gunugulla!

I told you we knew very little! We've been curious about Aquaponics for years but are only just now doing proper research.

From the research I did today I understand that to keep our system as simple as possible (no sump) we are best limiting our fish population so the single grow bed of approx 410 liter capacity (this is a total capacity including media) can cope with the fish by products.

I'm yet to figure out how many liters of water the grow bed will hold once filled with gravel.

We have other "conventional" vegetable gardens which are irrigated from our duck pond - so we are primarily interested in aquaponics for the fish - there's not much pressure on the grow bed to be hugely productive.

The FT will hold approx 1,100 liters of we fill it to 35cm from the top. I've read that this will support 40-80 fish but should we play it safe & start with just 20 or so?

I would love to have either Jade Perch or Silver Perch in the FT but we may be limited by what fish will tolerate a Sydney winter... (Read: more research required!)

Welcome SydneyChick!

Silver Perch are far more tolerant of a range of temperatures than Jade Perch, however they are a bit slower growing and don't eat when the water temps get too low. People will usually run trout over winter as they grow fast and like the cold water, but they can't handle the heat. Silver Perch and Tandanus Catfish are probably two of the better, readily available fish that will handle year round temperatures, you'll just need to wait longer to harvest them.

When calculating the amount of fish you can keep, focus more on the grow beds than the water volume of the fish tanks. The grow beds are your 'filters', so the bigger the fiter, the more fish your system can handle. Generally, for native fish you calculate 20-25lt of filtration (the wet media in your grow bed) per 500g fish (generally that's a table size fish) as a minimum. For fish like trout you need more filtration, 30lt minimum, but more is definitely better as they are fast growing messy fish.

Without having to add in other filters and mineralisation tanks, I'd be inclined to get at least one more IBC and cut it in half vertically to create two more grow beds. That will give you plenty of productive grow bed space, and more than enough filtration to keep a decent amount of fish for consumption.

Depending on the media in the GB, water volume could be in the range of 25 - 40% of the total volume.



I've never used one, but I think standard IBCs hold 1000l, but say 900l if you chop the top off, and you'd probably not want to fill it to within 35 (I assume you meant mm rather than cm) of the rim, as no doubt some will splash out during feeding, so actual water volume may be around 800-850l max. If you were to put 80 fish in there, you'd be close to the ridiculously high one fish per 10litre density that gets bandied about the internet. The more you pack them in the closer you are to disaster if the pumps stop. You'll get away with it for a while while they are very small, but once they grow you will have serious problems.
I'd start with 25 - 30 fish, but you will need more GB volume, as Azira said above.

Oh dear.

Don't really want more grow beds in the current space. Is there any way to make it work with just one grow bed?

Or are we going to have to move the system?

Limit yourself to ~15-20 fish should be ok with 400l wet media in the GB, or else run pipes to GBs in a different location.

..
Where in Sydney are you..
I have my new system working without grow beds.. but with extra filtration ..
So far so good..
It has one bed, but without any real plants..
ATM I have about 100 silver perch fingerlings, which is way too many to be realistic..
The waste goes off to other gardens..
..
.

BuiDoi - we are in Turramurra NSW ... Your excess waste - does it go to soil garden beds or Aquaponics beds?

Hi SydneyChick, I have a similar sized IBC system with a 1/3 IBC growbed, a 1/2 barrel GB and 20 towers and 2/3 IBC sump. There is plenty of biofiltration for my 25 rainbow trout I started with in March but I couldn't get enough plant growth over winter to take up all the nitrates produced. High nitrates can inhibit plant growth and make the trout taste swampy, so I have to do weekly ~30% water changes and top up with tankwater. The garden gets the fishy water, but its a pain and a waste of water. I am now down to 12 trout 30+cm with two in the fridge prepped for dinner tonight. I am hoping that fewer fish and more spring plant growth will solve my excessive nitrate problem. Also, with thd weather warming up I will only have another month before the water gets too warm for them so trout is on the weekly menu and has been for a while.

+1 for Gunagulla & Azira's advice on stocking rates.

I would have been better to start with 15 fish and save myself some hassles, or build more growbeds! BTW towers are high maintenance so I have found, prone to leaks and blockages. That said, it is great fun learning what works for you. Enjoy the journey

Some questions to ask yourself. Do you have a ready source of chlorine free top up water if you need to do unexpected or regular water changes? How many trout a week do you think you can eat between August and October? Or do you have freezer space to store them or hungry friends and family to give them to?

Hi Joc! I love fish and so do most family members. We also have an upright freezer so freezing fish is no problem....

After much thought today, the new plan is to purchase 2 more IBCs and clear out an old shed in the backyard and make space to put two IBC FTs in there.

Then we will put 4 IBC grow beds in a sunny spot outside the shed with plumbing running through the wall of the shed.

2 grow beds per FT should be enough to support around 20 fish per tank right?

If the grow beds are lower than the FTS - how do I get the cleaned water back up to the FTs once it has cycled through the GBs?

Final question - are the UV stabilized black plastic IBCs worth the extra money?

I have found a local supplier, but they are twice the price of "normal" white IBCs (though apparently they have never been used so would need only a cursory rinse before using for Aquaponics)

BOTH....

It first goes into a digester. A mineraliser ... where the foul stuff is broken down to a sweet smelling liquid.. like worm juice...
The problem is that you do need a good air supply..
The clay-ball bed is just a flood and drain device to help with the remaining ammonia etc..

Don't think that I have some magic that allows overpopulation of fish.. I will soonneed to reduce the numbers as they grow..

Peter..

PS...I would be inclined to go with the minimum number of fish and then finish the new beds etc...

Two IBC half GB's per FT should be alright for around 20 Silver Perch each. You can always start with less and add more fingerlings later too, as larger Silver Perch will usually tolerate smaller ones. That way you will also have a more steady supply of fish, rather than a big harvest in one go. With staggered fish sizes there should be less stress on the GB's too.

With two FT's you could have two different types of fish in both too, try trout over winter then put in a bunch of something else after trout season is up. Catfish, maybe the Jade Perch if your area gets warm enough, there are a few to pick from.

Repeating myself from BYP, but if you get a sump tank then you can set up a CHIFT PIST system, I *think* if you run it continuous flow, rather than with siphons, you can get away with a smaller sump, but you'll have to check as I'm not 100% sure.


I wouldn't bother as the black will just absorb heat, and the normal white IBC's can be painted, or you can clad the frame in something to insulate it and shield it a bit too.

F&D is fine. My big system (larger WB system in sig) has a 9500l FT above all the GBs, and a ST at the bottom, from where the water is pumped back up. I run it flood and drain, one pump 7 mins per hour, and the other pump 15 mins per 2 hours, with 225 fish. I do filter out most of the solids, which go to water which is pumped through WBs.

Is there any way to avoid a sump tank? If not - how big would the sump have to be for the type of setup we're planning?

Gunagulla - so do I understand correctly... you have one pump to send the dirty water to the grow beds and another to send the clean water from the GBs (or ST) back to the fishes?

Buidoi- where'd you get your Silver Perch? I'm starting to think they're our best option but livefish.com.au had nothing in stock when I looked...

Azira - I'm planning to place the FTs in the shed so they'll be fully shaded. I just thought the UV stabilized black plastic might make the grow beds last a bit longer???