I did an interesting experiment today and took some photos for others to see the results. I created containers with different sizes of grit as follows:
- 3/16 inch crushed and washed rock, which was sourced as Cherrystone #2 poultry grit
- 1/8 inch crushed and washed rock, which was sourced as Pumice #8
- 1/12 inch crushed and washed sand, which was filtered from Olympia #2 sand
- 1/20 inch crushed and washed sand, which was filtered from Olympia #2 sand
- Extremely small particles, which were from Olympia #2 sand
I dyed the water with green food color so that the perched water table would be easier to see on the sides of plastic container cups. I marked the level of the perched water table with a green line in the first photo.
The results of the test:
1: Tapla was right that the two particles that are larger than 1/10 of an inch did not have any perched water. These are the 3/16-inch and 1/8-inch samples.
2: The 1/12 inch rock had only one inch of perched water, and honestly, if this were part of a gritty mix with turface, I think such a small reservoir of water at the bottom would be a good thing, as the turface would quickly soak it up over the first day or two. At a minimum, such a small level of perched water seems inconsequential. I would be interested to hear what Tapla thinks about that.
3: The 1/20 inch rock had two inches of perched water, and that looks like too much for a container "purist" who wants to use larger particle sizes to keep perched water low.
4: The container with small particles was totally out of control, with perched water going all the way to the top of the soil level. I am sure it would have gone higher if I had added more soil.
