Dan Crawford said:
Hi and welcome!
Taking the braces off isn't easy but it certainly is possible. I've done it on a 6mm 80cm tank and it's ok, 90cm maybe pushing it, i don't know. A stanley knife is the way to do it and loads of patients. Oh, and once you've removed the braces, never fill the tank all the way to the top, be sure to only fill it to about 50mm before the top as silicone is at it's weakest there.
I took all the braces off my brand new no-name tank (it had braces on all four sides), 45 x 37.5 x 37.5 cm, no problems. (I fill it to less than 1cm from the top.) however, the glass thickness to tank size ratio is probably greater on this sized tank - I think it's the same 6mm glass that would be used to make a 60 x 30 x 37.5 tank. There's a few mm of bowing, but it's not visible to the naked eye.
What I did find when I was doing it was that it was impossible to get a stanley blade between the tank wall and the brace, so I had to use a razor blade in the end. Of course, you have to be very careful because of the double edge, but what worked best in the end was to get the blade down through the silicone, hold it top and bottom, and drag it along the seam with a see-sawing motion. Once I had this technique going I could go through about 30cm per minute.
Even though I took care, and have handled razor blades before, my fingers were covered in tiny cuts when I finished (no horrible disasters though), so I'll say it again - TAKE CARE IF YOU'RE USING A BLADE!
Most fish shops have there own local tank maker, always worth asking at the shop if they can make you a braceless tank from the start. They might have to speak to the maker and get back to you, but you'd at least have another price and option.
Lastly, if you're setting up a tank from scratch, have you done a budget of EVERYTHING you'll need to buy to set up this tank (filter material, substrate, chemicals, plants, fish, water changing equipment, scissors - I mean everything)?
If you do this honestly, then you might find the difference between hacking up a clearseal tank and buying what you really want from the start only makes 1 or 2% difference to the total cost of the project - at which point you might decide to wait till you can afford the tank you want!
Enjoy whatever you go with, don't cut yourself!!
Mark