i personally prefer the natural orange sand!-) black shows all the crud and white is as bad had both, ive used a fine orange kiln dried sand (as used to sand block paving) in my 35 and love it.
not sure, there are a few types here in the uk but the one ive used is very orange like this... most sand is safe, i cant think of a time where ive used a random sand and had a problem and a i have tryed loads
