Personally, I don't know why you need all new sand. If the sandbed is indeed dead, you can rinse it out & reuse. There are many reefers here with healthy tanks who can offer you a cup of their sand chock full of good creatures to seed it.
IMO, I don't like the look of bb, 1-2 inches of sand is my preference. Sure, a bit more more maintenance, but its worth it to me.
by my parents house in az there is one of the largest hydroponic tomato farms there is. because they are smack dab in the middle of the desert. i cant even get tomatos like that here in the mid west. my point being is that when you attempt to play god, which is what we are doing. you have to replicate nature the best as possible. my experiance with hydroponics has showen me this by that fact i cant get a good tomato here anywhere like im used to. and there is no 2 inch sand bed in the ocean, so i will keep going with the dsb. it just has to be replicated as closely to nature and in nature that sand is moved around by critters i nolonger have but need.
it may be to much maintanice for you. every post with an attitude try and remember the golden rule.
I'm going to let this slide because I am going to assume you don't know any better. There was no attitude in my post but you'll certainly get it going forward. Not everyone has time to manage a sandbed and I was saying the extra maintenance required to properly maintain one is not always something that everyone has time for. I'll make sure I don't trouble you with advice again.