I'd find out if it's tempered first and if it is I'd walk away. I've cut a few tanks apart in my day and you always end up chipping the edges, even if only slightly. The problem with tempered glass is it won't shatter from small chips but there's a possibility the internally stressed glass structure would be compromised meaning it could blow out later, and with 900 gallons behind it, it's simply just not worth the risk.

With that said cutting the tank apart isn't that hard. Remove inside beads first as well as any bracing if present. Plastic bracing will likely have to be scarified. Cut side seams first then pull the glass back to break the seal on the base, finish with knife. I'd use an x acto knife, you can actually get sets like this which work well. Getting the blade in can be tricky depending how the tank was assembled but if you start at one side and use some leverage you can usually work your way through the seam with ease. Personally never had much luck with piano wire.

I have only taken one tank apart and don't know how thick piano wire is.
But I went to a music place and got the smallest broken guitar string for free and used that.
As mentioned, I wrapped the string around two wooden dowels and see-sawed my way through.
Good luck, its a process!

Tank is not tempered thankfully,just highly overbuilt. at one time it housed a black tip reef shark but was used for freshwater up until it was shut down. I will update this thread on how it goes. Definitely going to be interesting especially when we set it up in the lfs as a display tank.

Btw thank you for advice and tips it is helpful

Use a product called Goof Off, it will soften the silicon to make it easier to cut threw with the wire.

I used a g string... The thinest guitar string I could find. Went through a few but they are cheap and very thin. Worked quite well.

Saw that and immediately tried to figure out how you would use a G string :twised:

You don't want to be wearing lots of heavy clothing if your gonna jump in there and start cutting out silicone