I've used haydite with good results for a few years now. I get it at a local landscape supply company that sells mostly top soil, fill sand, gravel, crushed lava, etc.
I mix mine with composted pine bark and course sand. So far, so good.
The stuff here is grey in color and has a more natural color, better than anything I've used.
It's also cheap! Less than $10 for 75 lbs.
And they don't mind my sifting it before I pay for it.