hi
i have used my sure flo back pack for pre treating conserv roofs with an alkaline cleaner , and also to apply gg3 to really dirty first cleans, then wash / rinse of using van mount. give it a good rinse out after ,and run pure water through the pump for a while to clean it after , been doing it regular for over 12 mths now - not damaged pump yet, and i still use it to clean the odd house here and there no probs.
daz