Join Date: Jun 2015
Location: Victoria, BC, Canada
From all the reading I have done, it is an issue when air can't get through the particles, so, finer particles will pack more.
The scenes I have seen done with steep slopes use large particles (read: ADA Power Sand) that do not get crushed/packed (e.g pumice, expanded volcanic rock, crushed lava rock- all with lots of air pockets and with substance). In these scenarios too the aquascapers use material to help bank the substrate so it doesn't just end up leveling out.
Other issues with steep slopes have to do with properly supporting any heavy or large prices of hardscape.
If you do a YouTube search using "James Findley Altitude" and watch the whole thing you will see exactly what I mean.
I do a lot of container gardening and the principle is similar, use coarse material to make sure there are micro air pockets which help keep the plant roots healthy. ADA's Power Sand looks a lot like the perlite commonly used by gardeners, except the power sand is darker and also feels more hard, it doesn't crush easily unlike perlite.
Hope it helps.
Daisy Mae V
According to my husband, I have a habit of jumping right in!