Dude,
Keep the rock and sand. The problems you're experiencing are a PIA, but not uncommon. You aren't going to find sterile liverock - what would the point of that be. I mean, yea it would be great if you could, but the real world is where we live. Spores of all kinds of crap infests liverock of all types, and from all places. Problem algaes are everywhere - it's just one of the laws of this hobby. You just have to do what everyone else does, and learn how to deal with it. If not now, then eventually - I say better now than when you're system is full blown. Bryopsis sucks, but it's not indestructable, you can keep it under control by limiting/exporting nutrients and predation.
DJ
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