How Shallow in fine DSB?

[Todd March]

Using sugar size argagonite in a 20 gallon tank (24X13X16), how shallow do you think one could make a DSB that is still effective–particualrily for denitrification?

I was hoping to get by with around 3 inches, maybe a little more, but well under 4".

Thanks,

Todd

 

[danmhippo]

If you can make it 3 inches, you might as well make it 4. Why skimp on the part that would make your nitrate nightmare go away?