Backyard Aquaponics
A place to discuss aquaponics

What wood do you use under the growbed when you offset ? Can you use mgp10 building pine or does it have nasties that can leach out when splashed?

I noticed in this picture that my pallet bottoms are the same and have 6 feet so do you just balance or do you secure them on?

If you're using the pallet as the GB frame, it should sit well on top of the FT/ST if you've got the FT/ST frame as shown in the photo. For extra security, you can use some stainless steel straps just in case. You can also install a couple of diagonal braces from the lower frame to the GB for added safety.

It's a good thing to educate any "small people" that the system is not a jungle gym, providing a step or box will mitigate the risk of a child climbing up the system and pulling the GB down on top of themselves.

If you want a high-tech solution, several people have installed roller systems where the GB can be moved forward and back over the top of the lower tank.

A significant issue with this configuration is ensuring the "spikes" of the IBC frame around the FT/ST which are pointing downwards can support the weight of the GB when full, without sinking into the ground, and without bending. A "trim" of wood can be used, and as its a long way from water, fish and food, you can use whatever wood you like.

I would definitely secure the bed to the IBC below.

Yes you can use untreated MGP 10 pine but it would probably only last about 5 years. Less if used for structural purposes.

We were only meant to be in our current house for 5 years at most so I did use a bit of pine that I had around the place to build bits of my system (non structural only). The moisture and warm temperatures are almost guaranteed to rot a non rot resistant timber like pine.

I'll be shortly selling some Californian redwood which is ideal for use in greenhouses because it is rot resistant. However, since I'm such a distance from you you would be better off getting some Australian cypress pine from your local hardware. It will be more expensive then the redwood but available just down the road.

If you were coming over this way though...

So I got this pile for free from bunnings but I'm worried about arsnic in treated timbers getting splashed by fish and outlet of growbed.

5 years is ideal its just for the students systems.

5 years until it falls to bits.

If there is any sort of load on it then less until it breaks. A lot less.

Yeah good point.

I'm looking at the pic again - our pallets have the crossbar bent up so its just 6 feet and thats why we have to have supports. If we didn't we could just spin 90 degrees and push a little bit out to access fish tank.


this is the timber we had.

If all that timber is MGP10, it's normally untreated so "safe" to around AP systems; noting that it's untreated and intended for indoor use, it's not going to last long in the outdoors when exposed to the elements. You could protect it a little by painting it, but for the amount of time and $$$ required, I'd be looking for two lengths of untreated hardwood, or two lengths of box steel which can be easily bolted to the pallet "feet" (both can be scrounged at a salvage yard for almost nothing).

thanks wabbit good idea - I have a carpenter dad and there are plenty of metal works in warragul. Will use the timber for barrel beds.

I wouldn't use it structurally especially not in a public installation. If it breaks and some one was hurt....

Hardwood can last longer but it depends on the species. Tasmanian Oak for example is not a species of tree but a marketting brand so they can sell a bunch of Eucalyptus wood under the one name. If you happen to get a peice of tassie oak that is mess mate it will last quite a while. If it is one of the other species like mana gum, vic ash or mountain ash then it may not last any longer than the pine.

For the quantities we are talking buy some metal or Australian cypress pine, it wont cost you much and it will give piece of mind.

Another idea for ya..

If you have access to free wooden pallets (many places give them away) you could place a couple them on their sides, and screw them together. This is how I've raised some IBC growbeds on one of my systems and it's rock solid when the pallets are at right angles to eachother:

More uses for pallets. I have access to lots for free also...great idea.Here, we have to keep them off the ground or the termites will eat them up in a year or two.

I am using treated pine with my timber, 90/35mm, but I painted it with a uv treated bondcreet outdoors product, that I picked up for free, its about $27 per litre in the shops, you don’t need to worry about runoff if you use this product, as it water repellent, yes it is a bit costly but, no termites and no rot in direct sunlight for $27 is good insurance, well I think so,

Wait for it?

Sorry double post

In some cases sealing woods that are prone to rot like radiata pine or vic ash can do little to protect them. If it were possible to completely seal such pieces of wood then it might work but invariably the seal is not 100% perfect and this can first allow moisture into a piece of wood and then moisture that has wicked away from the point of penetration becomes trapped under the sealing layer. This can actually accelerate the rate at which wood rots.

For example in a house the painted weather boards are protected on the outside of the wood but they are also free to dry because the back of the board is unpainted. On an adjacent pergola even though it may be painted and made from a more durable wood than the pine weather boards it can often rot away first and be collapsing even when the weather boards still have plenty of life left in them.

Also when I looked up bondcrete I found this:



You would still have the same problems though as I discussed above.

Good point Stu. Make sure that you seal/paint the ends, because that's where the xylem and phloem are most exposed and they will continue to wick water for a long time after they are cut. The reason you see so many fence section left exposed to the ground that rot from the ground up several inches, and the same fence left with an air gap doesn't do that.