Tempered glass as media?

[jim mckee]

I have broken tempered glass from sheets of 3/8" thick glass.

It doesnt have sharp edges or shards .

Any thoughts on using it for grow media?

jim

[Meir Lazar]

A few thoughts on the matter.

On the positive side, glass is chemically inert so ph drift and chemical leaching won't be an issue. Also, it is probably a lot lighter than gravel so easier to move the grow beds.

On the flip side, glass is very smooth so bacterial action would be much less than any non-smooth media such as gravel or clay balls. Also, even though you may not have to worry about being cut up, sliding your hand through several inches of broken tempered glass probably doesn't feel very pleasant.

I'm also looking into alternatives to gravel (too heavy), clay balls (too expensive), lava rocks (not ph neutral and rough on hands). But have yet not found a cheap, lightweight, ph stable media.

[jim mckee]

Maybe one could make their own clay media.

Build an extruder from pvc to make to make a hollow cylinder with 1 spit edge. Allot of chopping to length though. Then Kiln them?

Or make sheets of clay and cut into cubes with a pizza cutter.

Depends on the clay cost, store bought isnt cheap I guess one could use natural clay.

[Meir Lazar]

You could certainly try, although I imagine it's a lot of work and you may not get the lightness of the clay they use since the process requires a lot of heat (about 2000 degrees F) to "puff" them out.You will also have to filter out the contaminants and debris (if you want decent quality)

But yeah clay is cheap (if you source it from your ground) and if you want to spend the time and effort, kiln away.

Otherwise, you may want to look into Coconut fiber, perlite, vermiculite, etc.

Some controversial items to look into is packing peanuts, ground up tires, and plastic bottle caps.

[Vlad Jovanovic]

You might try expanded shale.

[Jonathan Kadish NYC AA Chair]

If you put the glass in a tumbler for a few days it would probably get to a nice mat finnish and the bacteria might grow on it.

[TCLynx]

Might be worth a very small scale trial.  They do make media out of recycled glass (grow stones) but that looks much like lava rocks.

Biggies issue I see with glass is if it's clear, it might have detrimental light and heat effects down in the grow beds.  And 3/8" glass is going to be definitely on the small side for use as grow bed media.  Generally the 1/2" to 3/4" size range is preferred.

[Charlotte Seibert]

What if you just mixed it with another media?

[Ronald Wickline]

Just a thought.  Has anyone tried glass marbles, maybe mixed with clay or pea gravel?
 
Meir Lazar said:

A few thoughts on the matter.

On the positive side, glass is chemically inert so ph drift and chemical leaching won't be an issue. Also, it is probably a lot lighter than gravel so easier to move the grow beds.

On the flip side, glass is very smooth so bacterial action would be much less than any non-smooth media such as gravel or clay balls. Also, even though you may not have to worry about being cut up, sliding your hand through several inches of broken tempered glass probably doesn't feel very pleasant.

I'm also looking into alternatives to gravel (too heavy), clay balls (too expensive), lava rocks (not ph neutral and rough on hands). But have yet not found a cheap, lightweight, ph stable media.

[TCLynx]

Might work Ronald but like others have said, they will be smooth so won't provide as good a surface area for bacteria or roots to grab and the light penetrating could be a problem.  And I doubt the cost would be all that worth while.

[Ronald Wickline]

Just wondering.  Marbles can be purchased in bulk for $1.00 a pound and are about as smooth as human teeth.  The manufacturing process causes lots of micro surface structure, unlike broken glass which fractures at the molecular level.

[TCLynx]

$1 a pound sounds kinda pricy (well maybe not too bad compared to hydroton but by the pound hydroton will fill more space for the money.)

Expanded Shale is perhaps 50 cents a pound retail.

I can get six tons of 1/2" river rock delivered for around $500 (so that would put the river rock at less than 5 cents a pound.)

[Ronald Wickline]

I see your point.  I use pea gravel from a local supplier for $32 a ton and never needed anything else but it did make me stop and think  about seeing old glass in the local rivers with algae growing on it.  So if Jim has the time and desire to tumble the glass it should work fine (biologically).