Backyard Aquaponics
A place to discuss aquaponics

Run one bed CF, or two beds CF.
Add another barrel linked to sump.
Use IBC as sump.
Reconfigure system.

Yes, I've now incorporated a third IBC into the design that will act as the sump. This should solve the volume issue for flood and drain.

I've not posted in a while as I am still in the set up stage. Not too far off though. I'll post some pictures soon. I've had to remove about 8 cubic metres of sand and build a retaining wall.

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OK, so I started this build just after Christmas and four months later I am getting closer to finishing the site prep. There have been a few awesome moments, like hitting rock right where one of the support posts had to go for the fence retaining wall (jack hammer solved that), and then there was a soakwell I had to move (previous owners had built the limestone wall right over it.. doh). Lets not mention the 8 cubic metres (280 cubic feet) of soil I've had to dig out by hand.

Part of the slow progress is me trying to do this as cheaply as possible. To date, I've had to purchase the retaining wall posts and concrete, everything else has come second hand. I estimate Ive spent about $450 AUD (about $340 USD).

Remaining job for the site prep is to pave the bottom (I have all the pavers second hand from a path I demolished).

I promise there will be some aquaponics posts eventually

YAY!!!! Site preparations finished today. It's taken a while, but I'm ready to start on the aquaponics phase of the build. I now have two IBC and waiting on the third, which should arrive soon.

OK, I promised I would post some aquaponics pics. I've started the build. I now have all three IBCs that I need. 2x FT and 1x sump. There will be another 2 blue barrels added for the RAS filtration (RFF and bio). I've recently decided that, rather than build the grow beds above the tanks, I might place them in the front yard down the side of our driveway, which will get a lot more sun. OK, any feedback welcome.

Hi all,

So I'm starting to design the exact layout of the system and it's getting scary when you have to actually start cutting holes in things.

My current query is how large do my grow beds need to be? Now i know this is where it usually gets bogged down with stocking densities, surface area volume of media etc etc. I've seen there is a general rule of a 2:1 GB:FT ratio. My system will have 2000L on the FT side, which equates to a 4000L GB, which sounds like a lot! Now my system will have a RFF and a biofilter, which should cut down that figure.

Im not trying to push for absolute max stocking densities, but am thinking about a total of 40 fish.

If anyone can give me a rough idea/recommendation of what they would do on the GB side for a system this size i would appreciate it. The pictures above should give an idea of the layout thus far. As mentioned above, i can locate the GB down the side of the driveway (behind the wall at the back)

Can't give you an exact figure since I don't know how much is going to come out in the RFF. Figuring without adding in the RFF and just using the information in the first post below you should be fine for stocking 40 fish if you're growing them out to 1 lb each - even if you only have 2000L of dampened grow bed instead of 4000L.

http://www.backyardaquaponics.com/forum/viewtopic.php?f=12&t=6646

The maximum based on that 3 Kg/100L was around 120 (final weight 500gm each) fish using 2000L of dampened grow bed. I don't think I'd shrink the grow bed space any more than that (you wnat to grow plants too) but you can probably walk it backward using the numbers if you do. Got to get going

Hi Scotty,

Thanks for that rule of thumb link. I was hunting arround the forums, but this is great. The RFF and biofilters will be in 250L blue drums, not sure about the media for the biofilter yet, recommendations welcome.

For the grow beds, I will not be using IBCs. I have a few options for size and shape of the GB. It needs to be functional so i can reach everything, but was thinking of making it about an arm stretch wide and as long as I can make it. I could make it a single long bed or break it into sections. Any wisdom on this would help, and if anyone has links to non IBC and non commercial (i.e. DIY) GB designs that would be great.

A question: does it get any sun?
It looks like it is tucked between your garage and the neighbour so I guess not much sun.

Ok some calculations.

My system has 2000L FT. So with 2:1 ratio = 4000L GB

If I want flood drain GB the limiting factor becomes my sump size = 1000L

I assume I need to leave about 20% water in sump to cover pump = 800L

Assuming an IBC sized GB = 0.3 x 1.2 x 1m = 360L of media and a 6:4 ratio of media to water = 144L water (let's call it 150)

800L sump capacity ÷ 150L GB = 5.3 IBC sized GBs, let's call it 5.

Given the 2:1 ratio GB to FT a 4000L GB system would need 4000 ÷ 360L/IBC = approx 11 IBC GBs

So I would be 6 GB short of the recommended ratio. I would have the RFF and Biofilter taking up some slack, but I'm thinking not enough. The alternative is to run additional beds as constant flood systems.

Any opinions welcome, math checkers.

Hi Wilsil,

You are right, in winter the sun is going to be an issue, which is why I am now considering placing the GBs in the front yard on the other side of the wall.

re: grow beds - custom sized.

Check out Colums stuff - he builds grow beds with pond liner obtained via eBay.
eg. http://backyardaquaponics.com/forum/vie ... =1&t=21207
or this one viewtopic.php?f=8&t=27495&hilit=grow+bed+video
there are other examples around with similar type approaches, some with bricks/cinder blocks.
I have brought similar stuff to what Colum uses on eBay Au as well.

The other 'not too wide' option is to use something like bathtubs if you get them from salvage/GumTree
bit like Pete is doing ( viewtopic.php?f=18&t=28231 )
Stocktroughs work as well - Alliance Moulding do a couple of deep rectangular ones, but $200 or so.


Pond liner or tubs etc work with either wood or blocks (or both). If you build it in the trick will be with your plumbing. A very simple and low cost option is to use galvanised steel posts like they use for security fencing.
These can often be found around and tend to be much better than wood for under bed supports.

Good side with above options is you can have deeper beds which helps out with the fish side (wet media volume). Out front seems fine - in summer you will get some things to grow down that side on direct and reflected light.

I would divide up into multiple sections and maybe even consider a DWC.
If it is a long bed you will need multiple discharge pipes and if long and thin multiple standpipes.
The trickiest would be getting balanced flow if you are using siphons - CF and timer will be pretty easy.

Constant Flood doesn't require a large sump . You could run some beds with siphons and some as Constant Flood but remember you don't have to hit the 2:1 ratio - that was a guideline - What's really important is that you have enough filtration for the fish you have. Charlie was on the right track - be flexible, all the beds don't have to be run the same way.

FWIW, I believe for each IBC grow bed in the IBC of Aquaponics they suggest 12 fish grown out to 1 lb (454 g) so if you had 5 IBC grow beds that would be 60 fish. The link to the IBC of Aquaponics pdf is in the upper right hand corner of the BYAP page.

I really appreciate all your comments. I'll think this over. I was thinking I could actually spread the fish over the 3 IBCs and use pond liner to line the inside of my trench to make a 2000L sump. Hmmmm options options.