Backyard Aquaponics
A place to discuss aquaponics

I have an IBC tank available in my area and have seen many Aquaponic DIY systems using them .

However my question is that I have seen that you should have a ratio of 1:1 for the FT:GB so how do these work if you just cuttign the top quarted off the IBC tank?

anyone?

Dont worry about the 1:1/2:1 rule. So long as you only stock fish to the density your GB can support that's all that matters.

Plenty of people on here have started with a single cut down IBC.

Hi AAF

The simple answer is probably "it doesn't work" as follows:

1000 litre IBC, cut off the top quarter means you have a 750 litre fish tank and a 250 litre grow bed.

Fill the IBC to a sensible level and you probably have about 650 litres of water.

Fill the grow bed to a sensible level and you have about 200 litres of filtration. The actuall water holding capacity of the grow bed would only be around 80 litres (40%) after it is filled with media.

So your final figure is more like a 8:1 tank to grow bed ratio, not good if you want to run a number of fish . You might be better off getting 2 IBCs and cutting one in half.

In reality most aim for a ratio closer to 1:2 i.e. 1 part fish tank to 2 parts grow bed. So for a 1000 litre IBC that would be 2000 litres of grow beds.

Would it then be best ro runa a pond filter as well?

The fish stocking density is often referred to as 3kg/100L of GB.

200L of GB as per FF's numbers means you can support max 6kg of fish.

my first system is an IBC with the top cut off.
for price you can't beat it compared to purchased.
True you can only stock up to 8 - 9Kg of fish but the learning experience that this little system can give you is second to none.
you can build your system and can integrate it to a larger system later on once you have gained experience. or add another GB once things get to there limit.
hope you have fun.

regards
Matt

I cut mine so the grow bed is around 30cm deep. It ended up around the 700 litre mark on my IBC.

True, you'll never achieve the desired ratio with a single IBC but they can work so well.

I documented a build here;

http://synaptoman.wordpress.com/2009/03/11/aquaponics-101-its-so-easy/

And here is an early image.

I need some help

Did everyone have this lid on top?

How did you make it watertight?

The lid should be water tight, there should be a rubber ring seal in it.

I seen a post on another AP site where they cut 12" off the top of the IBC and used as a GB to get started. As his fish grew bigger and the waste load got heavier, they built another 3x6' GB on one side of of the FT, then later on build another GB on the other side. So looking at the whole system, you had the IBC FT in the middle with the lid GB on the backside and 3x6' built GB on each side, all the GB were sitting on the edge of the IBC FT and gravity drained back into the FT. I believe he welded back on the top horozontal metal IBC frame to support the GB and just used cinder blocks to support the lenght of the GB. Pretty simple, yet elegant design that I'm thinking of using to convert an old 400 gallon jacuzzi into a FT with gravity drained GB raditaing out on 3 or 4 sides.
I'll dig around and see if I can find pictures of that system.

Cory