As Jr pointed out, we used aquariumplants.com substrate (Black Diamond). 4 x 5g buckets provided a contoured bottom with a minimum depth of 3" to a maximum of 6". It comes in two other colors, Natural Amazon and Red River.
Each 5g bucket covers 12 sqft @ 3" depth for $65 and free shipping. For comparison, we used eco-complete in the 45g tall tank 5 x 20# bags @ $20 each + shipping, which provided a 3" - 4" depth. It would take 6 bags of eco-complete to cover the same area as a 5g bucket of this stuff.
According to aquariumplants.com, it's the same substrate used in their plant growing end of the business. Grain sizes range from 1.2 - 2.8mm. They also claim it doesn't cloud the water, found that to be untrue. The gravel was washed by placing a hose in the bucket and letting the dust rise to and over the top. I strongly recommend a strainer of some sort (colander?) be used to wash it. We have moved a piece or two of the driftwood and it kicks up a cloud each time.
We also are going to use their fertilizer pellets for the rooted plants and liquid concentrate for the tied off/floating plants.
Ok, cool. Are you guys dosing? I assume you are.