Should I change my sand substrate?

[febrocky]

When I set up my aquarium I put a type of live sand down and then on top of it I put a dry sand that is very fine. Now almost a year and a half after setting up the tank I’m getting annoyed with the fine white sand. I’m thinking about just siphoning out a lot of the fine sand and just adding another type of live sand on top of the remaining sand that won’t be show in my display because the base of my tank has a boarder. I know sand holds a lot of good and bad bacteria so I was thinking I’d remove and replace the back of the tanks sand one week and then in a week replace the front area of sand? I know that fully removing all of the fine sand probably won’t happen but I would like to try to put a not so fine sand on top to weigh things down a little bit and because I don’t exactly like how the fine sand looks. Is this a bad idea? Any input would be great, thanks

 

[Sniperhank]

When it comes to sand, there will always be settling. That's why people that try to mix crushed coral and sand always get crushed coral on top. If you want to replace things because you don't like it, you'll need to remove all of it. To do so one will need to be very careful as it is also supporting the rock structure in the system. Don't want a collapse that could break the glass...
But in terms of beneficial bacteria, in any established system the rock would have enough to keep the system going. One will want to do water changes after manual removal of the sand due to any gunk that is released from the sandbed and prevent any issues.