I have found live sand to have no measurable effect on reducing cycle time. Live rocks absolutely, live sand nope. Also, although they say not to rinse it, if you do so anyway, you will find lots of brown organic sludge and often fragments of man-made objects. The stuff is filthy; some of that may be beneficial bacteria, but who knows what else is in there? As far as I can see, Carib Sea live sand is just sand taken from beaches and put directly into bags, I don't think they've done any processing whatsoever. If so, hitchhikers can arrive in live sand just like in live rock. Also, if you actually read the label on the bag, the amount of made-up and unsubstantiated BS there is truly impressive. Personally, if you can get the same sand but non-live, you'll be better off for it and probably pay a lot less.