What is considered a deep sand bed?

[seafan]

I want to set up a 55gal tank with lr, and ls. Well I decided to have a 3" Sand bed to develop anoxic bacteria. Is this considered a DSB. I've heard its an all or nothing deal, either <1/2" or >3". Is this completely true?

 

[quarryshark]

A true DSB would be at least 4".

 

[BillyZ]

It's not "completely" true, nor false

There aren't any hard and fast rules, but in general most will say anything less that 3 or 4 inches they would consider a shallow sand bed (SSB) and anything 3 to 4 inches or more would be a DSB. I have about 3 to 4 inches of mixed sand and CC in my 55. So I guess I'm not in the deep end, nor the shallow end... I guess I'm in the wading pool... of sand )