Does the paper say at what point the sand bed gets deep enough not to have a negative effect? Is there such a point?solbby said:In a paper that studied the amount of nitrate and phosphate in core samples, at 1 inch there is no detectable nitrate phosphate accumulation! (I have the paper on my work computer, so tomorrow I will post the findings, unless I can find it here on MR). However, as you go deeper nitrate and phosphate are present in increasing amounts.
So if you going to have a SSB I would not go beyond an 1 inch deep, so that no anaerobic bacteria can be present.