Scotchgard algae resistant roofing system

I see PABCO “Paramount” claims to have a 20 year
Scotchgard algae resistant roofing system…
does this stuff really work? can it realle last 20 years - even in the Northwest???

Hasnt been around long enough,…so who knows…certainteed says 15yrs i believe…

I concur with what you are saying Kage.