changing substrate

[Invigor]

ok. I have ugly crushed coral that seems to attract diatoms (that brown algae) and i've noticed from a 33g fish tank I have with sugar sand, it doesn't brown.

Is there a way I can change my sandbed without causing too much of a catastrophe in my tank? I've got a 60x20x20 tank with about 1-2" of crushed coral. There's a smokin deal on sand right now in regina and was wanting to change. Any pros or cons? I've got about 80lbs of live rock to move, but that shouldn't be too much of a hassle, they're mostly large pieces.

also, in repiles, am I wrong about sugar sand? does it trap diatoms and become ugly brownish?

the tank has been up for about 1 year