Is there a UK source for good black sand? I'd like some to use as a cap atop a mineralized top soil base, but I'm having trouble sourcing it here as all the source I found seem to be in the US. All I've found is products such as Flourite Black Sand which is decent and which I use in a tank already, but it would cost a fortune for a large tank, and regular cheap sand works just as well over a soil underlay. I'm looking for something such as black pool filter sand or 3M Black Quartz Sand. I had also seen one which consisted of ceramically coated small grains which sounded interesting. I'd however perhaps prefer to avoid silica sand though, as the silica seems to result in algal problems for some, though I haven't been able to confirm that, unless others can?