No, just 'spotted' it. That's a lot of GG4 for a 650l tank if my maths is correct - over a litre? Must be joking.
"GG-4 in solution is 98.7% water, and the way it works is by creating a negative ion, non-magnetic surface on the pane. This does two things: first, it instantly breaks the bonds that hold particulates to the pane, and second, it prevents moisture from clinging to the pane. This leaves your customer with windows that shine like diamonds in the sun"