Rubber mulch
 

So I was at Lowes looking for some pea gravel for my 3rd system and I came across this. Do ya think it would work in hydroponics?

Shop Rubberific 0.8 Cu. Ft. Red Rubber Mulch at Lowes.com

I have considered using the rubber mulch before as well, however because of the coloring (dye) in it that I have been told leaches out (enough to stain cement), as well as other chemicals, fungicides etc.. that I'm sure it contains, I simply haven't wanted to use it.

Nice to know.... I didn't actually read the bag, just glanced at it. Thanks for the info

I can only tell you I purchased a bunch of it for some plants that were in the ground and they didn't not do well at all. In fact we had to pull it back away from the plants as they started to die. I don't know if it was the chemicals that your speaking of or the fact that the stuff gets hot. Whatever it is we won't be purchasing any more.

Yeah, I have the same concerns as those above. Also I wouldn't use any products that the manufacturer does not provide an msds for.

I just checked their site and they don't provide any real information on reactivity and such.

One thing I have though about is using some polyester (synthetic would work well) like the cushon (spelling?) padding. It is generally the same thing as STG. It holds a little bit of water, but lets excess drain and has enough airspace to let O2 in and let root grow.

Wash the stuff down real well to get rid of any trace from production and you get a nice clean non-reactive neutral material (all definitions to be able to be called polyester). Also a full synthetic polyester may or may not biodegrade (most don't) so you will have a medium that is reusable for a while. Not to mention it is dirt cheap (well probably cheaper than dirt, pardon the pun).

I got more information on polyester as a hydroponic material. Turns out that STG is made of polyester. A few things to consider with it is that it is not moisture wicking and will completely drain. So it is good for constant feed systems. (I experienced this personally, when one of my lettuce plants wilted and found that they polyester was not obsorbing the water and pulling up to the roots.) So a water introduction directly to the polyester is a good thing. I also have mine running at a constant cycle, so the water never stops running to the roots.

This seems to be a less known growing medium, but there are a few articals on it. It is non reactive, neutral, and safe. (you drink from polyester every time you have a drink in a plastic bottle. Soda and water bottles are often made from the same plastics that make polyester.)

The STG cubes I am using are working well. Most of my plant issues are self inflicted. (I am too nosey) You just have to remember to make sure your watering system will be able to provide adiquate watering to your plants, as the polyester is hydrophobic, and will not obsorbe the water directly, but will hold a little for a short time in the small pockets between the fibers.