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View Full Version : DIY Fiberglass Growbeds?



scotteboy
06-11-2011, 09:50 AM
Hi. I was looking at using 2 100gal water resevoirs, they cost around $180 each and are 4'x4'x14". The other option would be to build raised beds out of spruce lumber (4x8x 16") and then waterproof using ferrocement(heavy) or fiberglass fabric and resin (lightweight).

Has anyone made thier own gear out of fiberglass? Would it require a special type or sealer afterwars to make it non toxic?

I have a gallon of resin already from a different projects, and woud like to use it if it will work.

Cheers

jcoop
06-11-2011, 05:57 PM
Had thought about that also, seams like the cheapest way is maybe a wood box with a pond liner.

There is some great info and a couple threads on Ferrocement that looks good, just not sure of the cost and which coating would work best to seal it completely.

I am using a stock tank for the fish tank and mortar mixing tubs for the growbed.

John

JCO
06-11-2011, 06:51 PM
For all the POOP on fiberglass and other ways of making growbeds, contact Stucco....this forum...he's the resident expert.

Antonie_001
09-02-2011, 12:07 PM
Hi, I stood at the growbed crossroad a while ago. I considered my options 1. Wooden boxes with a liner, fibreglass boxes or IBC's cut and paint. The last factor that sent me on my way was the finaces. I made 4 wooden boxes. Locally i buy 19mm shutterboard(ply wood) in 2.4x1.2m sheets. I cut a box per sheet (+-2*0.6*0.3). I used wet/dry wood glue (This stuff is called : Sticks like sh*t. I kid you not) and screwed the box together. From here I lined it with chopped strand fibreglass (400g/m2) and general purpose resin. Make sure you understand how the fibreglass process works before you start. Everything you need must be there and within reach. Once you mix the catalist with the resin, your on your way and there is no turning back. Do this in a well ventilated place - the chemical reaction generates a lot of odours. I used the fibreglass on the inside because of a fairly easy water tight seal and structural strength. This box would contain almost half a ton of media and water at its fullest. I painted the outside of the box with an acrylic pond liner to prevent wood rot. I overshot my budget by 30%. I needed a new plan for the remaining 9 growbeds. I found some IBC's. Bought 2 to cut up (As in Murray's video). The first IBC looked OK after the top and bottom was cut. I fitted the piping and it worked like a charm. On opening the second one I smelled a strong soap smell. I washed it several times and still not better. To make it worse, it had a wax layer as well. I inquired about the previous content and was informed that it was used to store car wash soap...oh dread. This became my fibreglass mould for the remainder of the growbeds. I gave the cut box a rim with wood and proceeded to wax it some more on the inside (release agent). From there I started moulding my first complete fibreglass growbed. I put down 2 layers of glass (First one must become tachy before the second one is placed - maintain layer thickness). I added a coulering pigment to prevent the sun from penetrating from the side. Again I used 400g/m2 chopped strand with general purpose resin. Worked great. Pulling the growbed from the mold singlehanded is a mission, but you get the hang of it. After pulling the first box and inspecting it, I had my doubts about structural strength. I placed it on the block stand, adde the 13mm stone media, poured myself a tall whiskey and climbed in the growbed, sat on the dry media and enjoyed a good milestone(8:30pm).
Fibreglass moulding is not easy, but it works and it is pretty fast. I was able to mould 3 to 4 boxes per day (In good warm weather). I tried woven roven, also 400g/m2 (thought it would work easier......not), but found the chopped strand gave me a more sturdy box.
I'm still trying to sort out th pic thing - if you need pics, i'll find a way get them on.
I hope this helps. My system is going for a few months now and the fibreglass boxes (and the wooden boxes, for that matter) works great. They have a good managable volume and size.

urbanfarmer
09-02-2011, 04:15 PM
Had thought about that also, seams like the cheapest way is maybe a wood box with a pond liner.

There is some great info and a couple threads on Ferrocement that looks good, just not sure of the cost and which coating would work best to seal it completely.

I am using a stock tank for the fish tank and mortar mixing tubs for the growbed.

John
The only thing cheaper is a pond liner in the ground or building it out of dirt somehow maybe using the lay of the land to create some height if you are lucky enough (or the land without a pond liner HA). But yes, that's about the cheapest I have found! :-D

JCO
09-02-2011, 07:30 PM
You can get 10mil black plastic 20' wide X 100' long at HomeDepot (I've used it for years) for right at $200 bucks. Line wood grow beds with it or you can dig a pond, line it with used carpet padding (foam type thorughly inspected for sharp objects) before putting the liner in. You can either roll the plastic up over a burm of dirt and secure it with rocks or you can build up the sides around it with 1" X 6" boards and 4" X 4" posts bruied 2' to 3' deep and run it to the top and overlape it with a cover board. :mrgreen:

urbanfarmer
09-02-2011, 08:17 PM
You can get 10mil black plastic 20' wide X 100' long at HomeDepot (I've used it for years) for right at $200 bucks. Line wood grow beds with it or you can dig a pond, line it with used carpet padding (foam type thorughly inspected for sharp objects) before putting the liner in. You can either roll the plastic up over a burm of dirt and secure it with rocks or you can build up the sides around it with 1" X 6" boards and 4" X 4" posts bruied 2' to 3' deep and run it to the top and overlape it with a cover board. :mrgreen:
Do you special order this? Mine only carries up to 6 mil, which I have used successfully in the past. 20' x 100' cost me around $90 if memory serves well.

JCO
09-03-2011, 04:08 AM
Yes, it is a special order and it is tough plastic. :mrgreen:

Shas
12-08-2011, 01:14 AM
I painted the outside of the box with an acrylic pond liner to prevent wood rot. I overshot my budget by 30%.


Thanks for the chance to look over your shoulder.
I like the idea of lining a wooden growbox with fibreglass.
It has all the right properties and only one negative,
which is that it's easy for the DIY first-timer to screw up,
and there's no fixing a badly botched job of glass.
You are right to emphasize that.

I like your epiphany to use the IBC as a mold.
Perfect.

But Antonie, I'm afraid your 30% over
was spent on something you may regret-
Your beds may rot more quickly than if you had not added the sealer.
It's a common problem.
With a fibreglass inner lining I would leave the outer surface free to breathe.
Water WILL get into the wood and it needs to be able to evaporate.

The best cure is to use a rot-resistant species to begin with,
such as red cedar.
(what beautiful grow beds those would make!)

The other is to either seal all sides of the wood before glassing
(but the glass won't bind to the sealant
so now you'll have to screw the glass to the wood...).

The third is to seal all surfaces with fibreglass.
***

Someone asked about toxicity-
I've built a few boats,
and glass is the ONLY material I would consider
for drinking water tanks on a cruising boat.
Once the curing process is complete
and the surface well rinsed,
there are simply no toxins or chemical leaching.
It's about as close to a perfectly inert substance as you'll find.

foodchain
12-08-2011, 06:13 AM
I have some experience with glass. And some with molding it around stuff.
I would think that if you were to do it, pull the plastic out of the metal frame, and mold around the outside. Easier to pop off. The sheets will lay flatter and can be squeegied out to remove bubbles. This is more awkward though for a first timer. But by overlapping the sheets like paper meche, you should get thicker, inter woven shell. I question though, if this is actually cheaper than IBC's. In DFW, TX fiberglass in this volume is expensive. 55 gallon barrels at $15 each are cheaper, and less risk of me messing up. Just cut in half length wise. But man are they ugly.

Antonie_001
12-08-2011, 08:12 AM
Hi Shas, thanks for the great advice. I've had the 2am wake-up session about exactly that. I've sealed some pine a while ago with a water bases sealant and it rotted......What I'll do. When I see the rot settling in, I'll give the inner liner another coat of glass and let the wood fade away. It is treated shutter board, so hopely it will be a while.

Hi Foodchain, Thanks, you have a good point. I'll give it a go with the next mould. It seemed tidier to contain all the resin inside the mould.

foodchain
12-08-2011, 08:40 AM
When I used a blank for a mould, I would wrap it aluminum foil. It would just pop off then, and then you spend the time pealing off the foil. Was cheap enough.