Those of you trying to find a good grit for Al's gritty mix can use the following very cost-effective method:
1) Find a wholesale garden supplier who stocks Olympia #2 sand. This is sand with both coarse and fine components, but most importantly it is well-washed sand. It is a gorgeous color and the lack of dust really saves time.
2) Run that washed sand through a sieve that is 1/12th of an inch, and the grit that does not pass is what you can use in the gritty mix. Even filtering to 1/20th of an inch gives a grit that is FAR superior to any horticultural sand you can buy in a bag.
Olympia #2 sand can be purchased under $150 per cubic yard so you can get quite a lot of it cost-effectively. I lose about 50% of the volume filtering it. The left side of this photo is what you retain with a 1/20th of an inch sieve. The right side of this photo is what you retain with a 1/12th of an inch sieve. Al's theoretical ideal is 1/10th of an inch.
