Planted Tank Guru
Join Date: Nov 2009
Location: Missouri united states
BDBS is abbreviation for Black Diamond blasting media which is often sold at Tractor supply stores.
As mentioned,,most issues with soil leaching up through a sand cap is due to cap not being deep enough and or plant's being uprooted /moved frequently which don't do nothing for the plant's from growth stand point.
Ideally,we research the plant's first which gives us an idea on what plant's may do best in our tanks, and how they might grow with respect to height along with whether they are best suited for lower light intensity, low tech non CO2, or higher lighting,high tech CO2 injection.
I would not be afraid of two inches of soil and perhaps two or three inches of a cap be it sand or fine gravel.
Soil issues largely result of poor oxygen level's which are hard to realize in properly cared for tank's.
Soil is not for those who can't/won't leave plant's be, and most soils are good for a year or two before either need replacing,or water column dosing with nutrient's.
Can use clay,peat,mixed with the soil and maybe get another year before you start noticing plant growth not like it was when soil was newer.
Plant's been growing in dirt for eon's.