I have an old tank that has some cracks at one end below the waterline. Are there any chemicals that will breakdown the old silicone so that I can reuse the glass to make a smaller tank?

Just cut thru the silicone with a sharp thin blade and remove the old stuff where you need to with a single sided razorblade or similar.

New silicone will not stick (very well) to old silicone.

I have an old tank that has some cracks at one end below the waterline. Are there any chemicals that will breakdown the old silicone so that I can reuse the glass to make a smaller tank?

There's a chemical called elbow grease that when applied with a knife or razor blade is very effective...

I was afraid you were going to say that. Someone said that nail polish remover can break it down. Has anyone tryed it? If not then Oh well, sounds like it might have to be the hard way.

I was afraid you were going to say that. Someone said that nail polish remover can break it down. Has anyone tryed it? If not then Oh well, sounds like it might have to be the hard way.

It might slightly break it down, but only enough to get the last traces off after you've removed most of it with a razor. Silicone is pretty inert...I think any chemical enough to totally dissolve it will also dissolve the glass, the table it's sitting on and your hands.

Get a paint scraper. You need to put a bit of effort into it, but keep in mind that old silicone is MUCH easier to get off than new silicone. I learned this after getting silicone ALL over the inside of the tank and having to scrape it off!

no not a paint scraper, get a stiff back razor. have heard from others here that a paint scraper can scratch. the diffrence is that a scraper is made from a solid wedge shaped pice of steel while a stiff back razor is a scraper that has a stanley knife blade as the scraper.

sounds expencive but i got one from the $2 shop