Disassembling an aquarium.

To take a tank a part is far easier than you think, no probs.

You make a narrow wedge,never apply metal or hard plastics to glass this way!!!

Make the wedge out of 1 to 2 inch wide hard wood is best but pine is okay,it should end up at 4 to 6 inches long starting at the point to the other end that finishes at 20 mil thick.

Grind an ordinary steak knife or any fine bladed knife,i just rub it on the concrete until it gets very thin, at the knifes end 10 to 20 mil of the length of it to almost paper thin, this will allow you to cut through the silicon that holds the tank together.

As you cut and it will be hard to push it down between the glass edges, if it is catching on the glass to much start the wedge at the top and begin cutting under it,now start the wedge at the top with some pressure as you cut down the silicon seal, not a lot of pressure on the wedge and it will open the two walls of glass,just a little gap is needed,glass is a bit flexable and do the same the other end and then pull the wall that has each end cut a little towards you as you run the knife along the base in side the tank and that’s how you take a tank a part!

Trim the access silicon off the glass edges,clean the areas that you want to silicon again with a damp cloth and apply metho with a paper towel and its ready use again.

Photos in here.
https://southeastqueenslandm.aforumfree.com/t1898-pre-filter-building-instructions-for-reef-aquariums