new eheim spray bar vs rena xp spray bar

i like how the rena filters have an extension of the spray bar where you can either put the spray bar either lower or higher in the tank. since the winter is approaching my open top tanks are evaporating a lot quicker. this has been giving my a problem with my new eheim spray bar kit b/c i can't lower it deeper into the tank. does anyone have any ideas on how i can modify it to go deeper?