[geekdafied]

The only thing I found to prevent that is by siphoning it out from time to time. Over time, detritus and various organics produce acids when they deteriorate. The acids cause the sand particles to clump/solidify making your sandbed usless. This is why you dont use a DSB. Though this can happen even if you have a 2" sandbed except you didnt waste a lot of money buying more sand that clumps on you. Also a larger grain size such as .8-1.5mm size sand is less likely to solidify on you.