roscoe
Well-known member
If your looking for a good mix of fine and coarse substrate, check out Indo-Pacific Black. It's a good mix of white and black sand. Has a really cool salt and pepper look. I have used it now in 2 different tanks and it works pretty good. My MP20's are mounted on the back of my display and they do push the sand back a little from the front, but not so much that its bare.
There is a huge difference in flow stepping from the 20 to the 40. I have had both.