It's not a problem that has the same solution for everybody.
Like the SW guys who always run tanks uncovered, the solution is in eliminating the cause of bubbles bursting at the water surface. Depending on how the tank is outfitted, you can picture how that may or may not be achievable / affordable for all. The worst cases are usually where a fine spray hits the bottom of a glass top with a light fixture that's heated it to some degree. So that eliminating air getting drawn into plumbing lines and switching to wave type powerheads from air-driven devices become parts of a solution.
There are glass repair kits available (Eastwood isn't bad), but they are mostly cerium oxide pastes, requiring an investment of time, elbow grease and $. In the end I think replacing the glass becomes cheaper than this option.
Acrylic isn't the cheapest solution as even the thin sheets you can get at the box stores is multiples of glass cost, and they turn into surf boards in a heartbeat. The thicker acrylics can be a solution, but again availability and cost are an issue for most. Polycarbonate won't bend / warp but still needs to be cleaned and not easy to find.
Running it uncovered is a whole different discussion.
More food for thought: There's several reputable plastics houses that sell Lexan (polycarbonate) sheets in an array of thicknesses and sizes. Some will custom cut and some only stock dimensions. What I can't vouch for is how it would perform over a tank the size of a 75G. In my head I can see it sagging in the middle over time and I'm not sure of the proper way to polish it (Novus?).
