I don't know how loud the Sapphire is, but the Tunze 9002 was almost silent. Very, very quiet. Other items (lights/fans/etc) where much louder.
Honestly, you might want to reconsider the low iron glass being a necessity on such a thin tank, IMO. I think the difference on larger tanks is much more noticeable than on smaller ones with thin glass. Just my opinion though.
B, since you mentioned new as an option, check out the Solana & stand we have in stock. Use the 10% coupon code and the price goes from excellent to excellent less 10% MRSWAP097
I use a Tunze in my RSM and its located in my bedroom - the only thing i can hear is the canopy fan and even that is extremely quiet. Getting the tunze was the best move i made