Backyard Aquaponics
A place to discuss aquaponics

I intend this thread to be about supporting a growbed in the TOP part of an IBC cage.
I know the best way to do it is to use the bottom part of the cage, and cut a hole in the center to allow for the screw cap.
HOWEVER there are reasons when this is not possible. As for myself I have an IBC with a plastic base, and there is a support right in the center, making it perhaps unwise to cut it all out.
Someone on this forum had used steel strapping across the frame to add extra support for the growbed (who is this? I cannot find the pics again !)
Copying this idea I added 4x steel straps parallel to the steel bars (which are very weak rolled tubing). However after filling with water I found that the middle of the GB still bowed a fair bit.
To improve this I turned the steel bars 180deg to allow some clearance and added some timber to the middle two straps to fill the gap. I filled to the brim (200L) with water and currently leaving overnight to see how much everything bends.

Photo below shows IBC with top of cage removed and straps added. (Sorry about the long grass) Better pics coming tomorrow

you can buy square lengths of aluminium if I was setting up and Ibc like that I would buy a length of that and tech screw it into the frame instead of the builders strap

I wonder how much galvanic corrosion you would get between the zinc/steel and the aluminium.
It needs to be pretty strong, sooo much weight in 200L of gravel plus water...must be nearly a ton ...

200L of volume is going to be roughly 200kgs one way or another the i would only use galvanised steel or aluminium

yeah, maybe I should get some steel or something to screw in place.
btw if it was just full of water it would be 200kgs, but a 1/4 of a cubic meter of gravel will weigh much more than that ! Plus the water that in it as well.

I'm hoping others here who have done a similar thing will post their solution

Hi all,
I am just putting together my first AP system and was considering the same dilemmas for the GB's. What i have ended up doing was making some frames with some old 4x2 Jarrah timber. First i made 2 x inverted "U" supports that go across the beds side to side. Then another support in the middle at the back to give extra support. I have also put a couple extra support beams in to tie all of these together. I hope this will do. I cut me GB 350mm deep so it may be a little heaview than i first thought. I hope it is ok. Any thoughts?

I was lucky with mine, being a boilermaker I have access to 'offcuts' from work. Under one I used real offcuts of 25mm square hollow section, 5 accross the IBC, it has sagged in between but I am using pea gravel so it is a lot heavier. The other one I built a stand at work out of 40mm angle iron at put a piece of (not so much) offcut stainless steel plate under the whole tank. Would not recommend stainless due to the costs ($250+) but no reason you couldnt use 3mm steel plate.

Ok some stuff I learnt while doing a rigger's course..

easy stuff actually..
1 cubic m water = 1000kg = 1000lt's..
1 of concrete = 2.2-2.4 t
1 of steel = 8 t

so if you went on 200lt volume I would go for something in the 440-480kg range...
So say 1/2 ton of weight easy.. Better make the frame real strong..


Had a Look at your IBC frame is the base Plastic.. or just painted..
Me with your Frame..
I would separate the Base Plate off the frame.. turn the cage upside down and let the cut off tube rest on some solid timbers..
- Take the Base and run it across the Frame and then put the small cut-off section of frame on top and place the cut-top of the ibc in that..

I know that in the pic I don't have the Growbed resting on the frame of the Tank Frame but you get the idea I hope..[Because I used a Full IBC Tank as the FT and only half the frame I needed to make a frame to help support the GB above the FT..

Hope this helps you..

The base of the IBC cage is all plastic.
Also there is a support right in the center of the base that looks like it shouldn't be removed. So this means I cannot cut a hole for the screw cap

The hole doesn't have to be centered.

if the hole is for the IBC bladder screwcap it does.... Otherwise you would need to cut a hole and put another fitting into the bladder

Dont cut the cap. Cut the bladder where it won't hit supports.

Or use 50mm or 75mm pine sleepers under the bladder as support.

I wouldn't recommend using using timber. I used some when I first set mine up and I found it was always wet. Wether it be from splashing water or rain and eventually it bows. If you think about it, it is the same technique they used on bending the timbers for old boats, using weights and water to bend timber over time..but eventually, if not treated correctly would snap. Especially with the weights we are using. Could you imagine the carnage if your timber supports broke..

Check mine out, I actually cut all the supporting frames off from my IBC base and Ill tell you it is a very thin piece of galvanised sheeting when I was done. I am a mechanical engineer by trade and I calculated that if the base is supported equally in 3 sections as well as the front and back it will be more than enough to hold the weight of around 500kg.

My only question would be how thick is the plastic base? Try turning it upside down and walk on it and see how it fairs?

yeah, had a walk around Bunnings today looking at timber and steel. $13/m for 30x30mm RHS !!!
Decided to wait till the 3rd when the steel shops open to get some gal stuff.
Just going to put 4x supports across the frame of the FT and sit the GB on that.
Will just use some painted pine to block up the gap between the RHS and the recess in the GB. Doesn't matter if it turns to goo, plenty of support.
Personally I think just using the builders steel strapping would work fine but its not something you want to risk Might be low risk but big consequences

Some sort of hardwood would be fine though. Pine is rubbish.