Quote Originally Posted by MikeM670 View Post
Are you sure its silicone? That would not stain the glass. Is it calcium deposits? Let the vinegar sit on the area for a long time. You can also try CLR Cleaner that works great.

For silicone you need a brand new razor blade to remove that very fine layer. You can also try more extreme measures like turpentine or naphtha soap. The tank would need a very good cleaning afterwords so try and limit the area you apply those to.
There's definitely some silicone stains, as I am the one who has removed it. It's not just a tiny film. I got a brand new razor blade and it's not cutting it. I will try CLR. I have also heard that acetone might do the job. It's starting to be warmer here, so this part will be done outside, and I'll make sure to really clean it before going forward. Thanks, Mike. As always.