How deep to lay it
Lay about 2 to 3 inches where rooted plants will grow, and 1 to 2 inches is enough under a carpet or in a tank without plants. A slope from front to back gives tall plants deeper roots and makes the tank look deeper. Burrowing fish such as kuhli loaches want soft sand. Planted tank substrate · Decor and substrate
Why the same bed weighs so differently
Bags are sold by weight, but the bed is a volume, and substrates differ a lot in how much a cubic foot weighs. CaribSea’s Eco-Planted, a porous volcanic gravel, is 54 lb per cubic foot; its sands are 92 to 100 lb. So a 20 lb bag of Eco-Planted lays a little under 2 inches over a 20 long’s floor, and the same bag of Crystal River sand barely over 1 inch. Soils such as Fluval Stratum are lighter again; their makers give no density, so use the volume here and the bag’s own coverage.
Measuring the floor
Measure inside the glass, not the outside of the frame: a 20 long is 30¼ × 12½ inches outside but about 29½ × 11½ inside. For a corner or bowfront tank, measure the widest part and treat the answer as the most you will need. Then add the weight to the filled weight calculator.
CaribSea’s published densities
| Substrate | Grain | lb per cu ft | Bags |
|---|---|---|---|
| Eco-Planted Black | 0.25–7 mm | 54 | 20 lb |
| Eco-Planted Red | 3–6 mm | 54 | 20 lb |
| Moonlight Sand | 0.25–0.75 mm | 95 | 5 lb, 10 lb, 20 lb, 40 lb |
| Sunset Gold | 0.25–1 mm | 94 | 5 lb, 10 lb, 20 lb, 40 lb |
| Crystal River | 0.5–1 mm | 95 | 5 lb, 10 lb, 20 lb, 40 lb |
| Jungle River Sand | 0.5–1.5 mm | 100 | 5 lb, 10 lb, 20 lb, 40 lb |
| Torpedo Beach | 0.5–2 mm | 94 | 5 lb, 10 lb, 20 lb, 40 lb |
| Peace River | 1–2 mm | 93 | 5 lb, 10 lb, 20 lb, 40 lb |
| Maui Moon | 1.25–1.75 mm | 100 | 5 lb, 10 lb, 20 lb, 40 lb |
| Carolina Creek | 1–2.5 mm | 100 | 5 lb, 10 lb, 20 lb, 40 lb |
| Shadow Creek Sand | 1–3 mm | 100 | 5 lb, 10 lb, 20 lb, 40 lb |
| Midnight River | 1–4 mm | 93 | 5 lb, 10 lb, 20 lb, 40 lb |
| Gemstone Creek | 3–5 mm | 96 | 5 lb, 20 lb, 40 lb |
| Raven River Pebble | 6–14 mm | 100 | 5 lb, 10 lb, 20 lb, 40 lb |
| Zen Garden | 9.5–13 mm | 92 | 5 lb, 20 lb, 40 lb |
| Jelly Beans | 13–26 mm | 99 | 5 lb, 20 lb, 40 lb |
| African Cichlid Mix White Sand | 0.5–1.5 mm | 73 | 20 lb |
| African Cichlid Mix Sahara Sand | 0.5–1.5 mm | 92 | 20 lb |
| African Cichlid Mix Ivory Coast Sand | 1–2.5 mm | 94 | 20 lb |