That glass spray does work good. It makes the glass slippery.I have the same... love the dual blades and strong magnet on the .75" glass.
BUT, have you tried this!?
The combo of Fritz's smooth coating and the MAX is like butter!
For the tough stuff it's hard to beat the 4D ceramic blades. I use the plastic blades for the soft stuff if I keep up on the glass cleaning and if I don't clean my tank for awhile (seems to happen lots lately) I then use the ceramic blades because the plastic ones won't get the stuff off.
