GE I for windows and doors. The "kitchen and bath" or "tub and tile" have mildewcides. The correct tube is likely blue and white rather than red and white. Depending on where you live, you may find a store brand that says "safe for aquariums" on the label. We have a few around here, and they are slightly cheaper than the GE, even though, they are likely GE I that has been re-branded.
Join a fish club. Don't have one in your area? Start one.