I use a 50/50 mix of isopropyl alcohol and distilled water, it doesn't stink as much as most other options and it evaporates very cleanly.

A scraper/razor like the kind found in the paint section of hardware stores (STANLEY | Single Edge Razor Blades - 10 pack | Home Depot Canada) is also a great glass cleaning aid. Just be sure to keep it away from the silicone.

My tanks are built out of old glass windows that were stored in a barn. The above cleaning materials will also work on barn cat urine.