Backyard Aquaponics
A place to discuss aquaponics

Hi all,

Place where I work manufactures fibreglass tubes and pipes. I was thinking of perhaps using fibreglass pipe of around 3m long cust in half as grow beds, something like synaptoman has done in South Africa.

I will basically get them to make a sealed cyclinder then cut in half to make 2 long growbeds.

now a couple of questions:
Any idea what thikness I should ask them to make it?
What diameter do you think I should use. (80cm?)
How many standpipes for a 3m growbed ?
How many standpipes for a 6m growbed ?

What would the cost of these tubes be?

Good one skygazer - something I'd theorised about at one stage was getting my hands on some of this Iplex Flowtite Pipe http://www.iplex.com.au/products/flowtite-main.shtm

Other than probably having no chance of sourcing it and it being too expensive, I also wondered about compatability with a closed loop food producing system. As I understand it, some resins are more suitable than others.

As for you questions - required thickness would all depend upon things like how you intend to support it and the media you are going to use. Of course, the production method would also have some bearing (ie the nature of the fibreglass matting etc). As for width (diameter) - I'd be inclined to make it a metre or so. It is easy to reach into the middle of a bed that size from either side. Of course the nature of a semi circle is that the beds will be deeper in the middle than the sides, but this is not a major issue. As for standpipes, provided that the drain is sized appropriately for intended inflow into the bed - there is no real reason you need more than one if running flood and drain. Given the potential length of the bed though - I can see why you have raised the issue. If you are concerned about one blocking or the siphon breaking while there is still water travelling from the far end to the drain (if using autosiphon) then I guess you could put another in, but if so I'd be inclined to have one at the lowest end of the bed (have a very slight drop from one end to the other) and the other in the middle.

I'll be interested to see if you proceed with this idea - it's something I'm keen to explore further in relation to large diameter fibreglass or poly pipe.

Would it be cheaper than stailess steel?

A half cylinder made with ferrocement would be cheaper.

Thought fibreglass was prone to delamination if fibres are exposed. Do you intend to seal the cut edges?

For something this size, I would imagine that lining a frame would be cheaper.

Yes go with OBOs idea....

thanks for all the reply's.

I go and ask the guys in the workshop about options for potential delamination or other options like rectangle GB's.

I am keen to explore because they may cost me next to nothing if the machinery is ready to go. One of our machines can basically do this fully automated except for the ends, compared to a sqaure tube which would involve lots of labour either laying it up manually or creating a mould.

anyway I will go and have a chat to the guys and see what they have to say about it.

Last time they gave me a 4700L - 2m diamater x 1.5m tall tank for free.

If you can get them really cheap, perhaps you would think about round grow beds instead of trying to support the half tubes? There are many people out there who have lined a round galvanized ring and filled it for use as a grow bed.

Sky

Wasn't trying to be discouraging anything like that for free is great A halved cylinder should have reasonable strength because of the curved ends, providing it is not too long, and even then its doable by glassing a centre support across the top. Is it possible to get the cut surfaces gel coated?