Depth Profile
Front: 3cm — enough for carpeting plants and foreground species like dwarf baby tears.
Middle: 4-5cm — for crypts and smaller swords.
Back: 5-8cm — for deep-rooted plants like Amazon swords and vallisneria.
Why Sloping Helps
Sloped substrate creates visual depth — tank looks bigger. Also encourages debris to settle at front where it's easy to siphon.
A 5cm front to 10cm back slope is typical for 45cm wide tanks.
Anaerobic Pockets Risk
Substrate deeper than 10cm risks anaerobic (oxygen-free) zones, which release toxic hydrogen sulfide. Smells like rotten eggs.
Mitigate with Malaysian Trumpet Snails — they burrow and aerate. Or stick to 8cm max depth.
Dirted Tank Variation
Walstad dirted tanks: 2cm organic soil at base + 3cm cap of sand or gravel. Total 5cm.
Do NOT exceed 3cm soil layer — more risks flooding with anaerobic gas.