Backyard Aquaponics
A place to discuss aquaponics

would prove lighter and more surface area, also be a use for carbon which we have a bit or 2 spare...I like it!

Thanks for the interest. The glass can be had in different grades. It ranges in size from powder to 10 mm. The common size in the process I have used is 1 to 4 mm, which gives compost at a 50 to 50 percent mix a porosity greater than potting mix. The porosity can be measured and adjusted to some degree.

But in aquaponics I have seen only 10 mm plus stone used. But then I can visually see the glass at 1 to 4 mm easily retaining sufficient moisture for growth yet allowing excess to drain.

The objective is not so much creating an aquaponics set up but more of using the waste generated in a small remote community efficiently, and aquaponics might be the way to do that. Also I am looking to granulate the plastic waste and include that because I know plastic is an efficient surface on which to grow bacteria.
Glass has the same attribute.

It is not an idea as much as a need, because I have the waste stream and need a way of using it in a common sense manner.

Any help appreciated greatly.

I would be a bit dubious of a medium made from plastic - would be concerned about the potential leachates.

The finer the medium the faster it clogs up leading to anoxic conditions. 1 or 2mm is really sand and would clog very fast unless you remove solids beforehand. 4mm would be coarse sand and, I think, would clog fast. Try it, take pics, report back! Please!

I think the 10mm might work nicely as long as it was washed carefully to remove small bits. Is it sharp-edged? I'm just thinking in terms of digging around in it to plant things or releasing worms into it. Maybe fill the bottom half of the growbed with glass and the top half with something smoother.

The 10mm could be really interesting as a landscaping accent. Imagine doing a dry stream with a thick layer of sparkly glass for the water. What colors of glass can you get?

because of the carbon, black, for now :-) but surely some1 will colour it with some nasty substance that comes with it's own nasty leachate.
As for the grade, what size is the vermiculite F&F uses? perhaps a medium of gravel topped with expanded glass of 4-6mm?

I'm interested to know if that waste stream glass currently available is smooth edged or sharp?

If it is sharp, I would not want to put it into grow beds where one is likely to stick wet hands. (Wet hands and broken glass are a fast way to need stitches.) and if it is still sharp, then the worries of bits of glass in/on food become an issue since sharp edges are likely to chip and flake creating more fine bits.

If it has been smoothed already, then little extra effort is needed to make it safe to use.

If you grow carrots in glass do they come up allready sliced

It is pretty stuff. There is a place here where a town dumped it's incinerator slag for decades, then the ocean washed most of it away leaving a beach of 90% glass pebbles. People come with buckets, others just enjoy it and look for blue glass bits.

Before I worked with it, I'd want it tumbled so that it no longer had sharp edges, then the next concern would be it's lack of ability to absorb moisture and nutrients and with slick surfaces not being a good home for bacteria.

There are a LOT of uses for recycling glass. What type of glass is it? What quantities are you talking about?

oh, and Welcome aboard!

That's purdy Hydro. Amazing something as fiendishly evil as dumping slag on a beach could turn out so pretty

I hope I haven't posted this twice. Our reception just failed again. We live in a small community within a national park, which explains the background. I manage the campgrounds here and am responsible for the waste management. We have from 100 to 1000 people at any time. The waste stream is not huge, but glass accounts for about 60 per cent, and green waste about 10 per cent. The motivation was that if we could use it locally we could save transportation costs and also make it educationally interesting, especially with aquaponics.

The sliced carrots are an idea, although we will have to try a native bushfood perhaps.
The leachates I will check on. We have plastic strips already in a wet composting system which are used specifically for bacteria production, so we can run a test on the liquid for leacates.

The oxygen flow is an issue. I have run water through the glass on a continuous flow, and have noted that with an intermittent flow - as referred to in Joel's kit - I noted that there was good oxygen intake as the water subsided, sucking the oxygen in, especially with the 4mm grade.

The glass very quickly becomes smooth to touch, and even to rub within the hands. It looks pretty in a way, although mostly it is a colour of raw sugar or treacle. The beer bottles are predominant here, expecially at Xmas. Psychologically people do have a problem with it, understandibly. We have successfully used it in the potting mix, and are having the State health department look at it in terms of environmental health issues. Still waiting for the result. The glass dust which is created in the process is a concern which we have to put to rest.

The worms were okay in the mix after it had been used in compost and turned and watered a few times. There were a few initial sacrafices in my eagerness. The African night crawlers we are using though take to the extra water.

I will try it now with an intermittent flow, using compost tea as the nutrient; run the flow over the worms intermittently. The fish are growing but not yet of sufficient quantity, and I will try to incroporate them into the process as I go.

Any other thoughts will be greatly appreciated.

Wow, that's cool. Wish you the best of luck. But hey, if you have worms, a glass treatment plant for to remove sharp edges, and fish you're growing... Where the hell are the pictures man! Dodgy internet connection aside, lets see some piccies please.
Keep up the good work Ashley, You may find us all using recycled glass before long. The people interested in AP are usually enviro-minded, and LOVE using recycled materials if they can...

Ashley you have confirmed a question I've been meaning to ask for several days and exactly the concern that Rassd71 has highlighted....

The use of gravel, expanded clay, perlite etc has been successful in AP systems due mainly (IMHO) to the fact that these media contain large irregular surfaces and as in the case of the later mentioned media with many microscopic holes to retain oxygen, moisture and bacterial growth...

As highlighted by the "pretty" glass found on a beach and by suggestions of tumbling and noted by Ashley.... glass becomes very, (and I suspect uniformly) smooth.....

So while I'm sure it would be a worthwhile, pH nuetral component mix for media (AP or otherwise), I have some doubts as to whether or not it would be as effective in providing an environment for bacterial growth in comparison to other media....

I'd put it in the same sort of category as vermiculite, probably good for root crops....

Differences....wouldn't hold water very well, pH nuetral, durable, probably neligible release of any useful trace elements

Not sure I'd go as small as 4mm though if I was going to be used to entirely fill a growbed..... think 10mm (as suggested) might be a better size to allow for oxygen capture during a drain cycle....

Vermiculite, while fine and quite compact in smaller grades has an irrgegular and often pitted or even hollow subsurface to trap both moisture and oxygen.


Still, if it's cheap or free then why not use it..... give it a go....

I can't see the glass becoming completely smooth. There will always be small indentations that the bacteria can use. But, yes, the larger size would be better, the 4mm would start to act like sand beds and hold more water than you would want. Larger sized media drains faster.