Cleaning in tropical/hot climates

It can be a pain in the butt cleaning in hotter climates, and perhaps if you're using water fed poles you're faced with tougher challenges than the average joe, cleaning in somewhere like middlesborough, england. The states I know has plenty of diverse climates differing from state to state, and somewhere like Las Vegas presents more challenges for the window cleaner - even if they're using Water Fed Pole Systems.
People cleaning in hotter/tropical climates using WFP will often find themselves going through more water on a daily basis than someone perhaps in a colder climate. Often the windiws in a hot. tropical climate are a magnet for dirt and dust. And its not unheard of for window cleaners to have done a once around and only a few minutes later check backed on the panes and find there's dirt and dust that's settle on there.
So what's the solution? Well, it's often a case as with most things in water fed pole cleaning - a case of trial and error. One thing I've read about window cleaners is actually heating up the water from the van through portable convection heaters so that when it hits the window it has a better effect of removing the dirt, dust and general crap on the window. Another idea might be to try a solution/chemical to the water to make ensure that dust and dirt is repelled from the glass pane.
As it very rarely gets above 20 degrees in UK for most of the ye, us window cleaners here are blessed that we dont have to contend with this kind of problem. so i'd be interested in hearing how window cleaners elsewhere overcome this problem.
please comment and let us know your tips and tricks.