Backyard Aquaponics
A place to discuss aquaponics

I watched a documentary about Gen. Sherman a couple weeks ago, and they talked about the pontoon bridges they built back then to cross the rivers (and therby cause mayhem thoughout the South). Some civil engineering reenactors built a few pontoons and a short bridge. The materials they used were some collapsible wooden trusses, and canvas for skining the pontoon boats.

They said canvas will swell and become waterproof - I immediately thought that this could be useful for AP grow beds or tanks, if the canvas indeed can hold water, or at least some grow bed material.

Hex's fabric troughs ( http://www.backyardaquaponics.com/forum ... 0&start=90 ) could be made from organic cotton rather than synthetics, which would add to the feel-good quotient. I imagine that for tank use you'd have to keep the water from wicking or seeping into the ground?

Canvas I would imagine would be much more available in less developed regions of the world, unlike say EPDM or even concrete?

I wonder how the canvas goes for being truley water proof.. Here in Australia canvas water bags have been a bit of an icon for many many years. http://www.campout.com.au/carwaterbag.html

Though one of the points of a canvas water bag was that the water seeping through the canvas would evaporate, cooling the internal water. I wonder how much this might effect things, what sort of evaporation rates you may get.

Looks like for canoes and whatnot they paint it to make it totally watertight. If you used a safe paint that would be acceptable.

DD, from memory I think they used bitumen, or at least a bitumen based paint

The one site I looked at yesterday for canoes said you could use any cheap paint you have lying around.

Here's is an interesting link to concrete-impregnated canvas shelters:

http://www.wired.com/science/discoverie ... 5/03/66872

Actually, back during the American Civil War they used boiled linseed oil. Put on a couple of coats on the outside, let it dry, and it aids in the water repellency. Does'nt make it water proof, but it helps keep the pontoon bridge floating until a permeanant bridge could be constructed. Probably would do the same thing for your tank or growbed. (I'm not sure of its toxicity though.)

Kevin

don't start saying things like toxicity and linseed in the same sentence I put them on my loaves of bread every day

What - toxicities.....what do they taste like

linseeds taste like linseeds! I've never actually tasted any by themselves But, just for you Les, I will tomorrow

Nah! - I wanna know wot toxicities taste like

I don't think linseed is toxic, but boiled linseed oil most definately is. Actually, it's not boiled at all; they add heavy metals and some other stuff to make it dry faster.

You don't need a growbed to be entirely watertight if it's placed right over the fish tank, right? Although you would probably need a bigger pump if you want to use F&D..
If it's not placed over the tank though, something like Hex's troughs would do, but then you still need some water proof fabric or gutter under it.

Toxicities sure worked well if Jaymie's new avatar is any guide...seems like Mon has been hitting the hot stuff too

Sock full of walnuts...

Nova

lol...... its nudda tumar!