This system works very well because it takes off the stain, resurfaces the glass and when you add the protectant, it creates a hydrophyllic surface, making the water sheet off, which is great for repeated contact of water to glass (sprinklers), although, you may suggest to the customer that they should have their sprinklers rotated to avoid the staining again.
This protectant may maintain its hydrophillic properties for up to 2 years, but with repeated sprinkler contact, its best to reapply every 6 months.
Here's a link to a youtube video on how to apply NanoUltra. This customer uses it on beach front windows because of the sea water that gets on the glass and the water that falls from above when the tenants hose off their patios upstairs. http://www.youtube.com/watch?v=KX5-reyZuRA
It all depends on what type of stain your contending with? From there you can get a better understanding. With most of us we have found a suitable product. It's when dealing with "silicate deposits" does it become an issue.
For the most part those either have to be removed with polishing/abrading or an HF "hydrofluoric acid" (provided the stain is on the "air side" ) otherwise you run the risk of getting "tin etch haze" if applied to the "tin side" of glass ...a chemical reaction between the acid & tin in the glass.
Biggest benefit is if removal is successful applying a good "sealant" is vital even more so in problematic area's.
Soap and water usually works fine for us although I imagine it depends largely on the mineral content of the water. We have one customer whose sprinklers are controlled by the city in which the business resides. We can't seem to get anyone to adjust them although we ask each year. Perhaps we may look into a sealant even though we have become quite adept at removing the stains every 14 days all summer long.
