A film on top of your tank? You are sure no one has been spraying Febreeze around or anything?
Also, when's the last time you did a water change, your feeding schedule, stocking list, and parameters? I think the film should be addressed before you buy more equipment.
55gPLANTED:Rainbows/Loaches/Garras|30gVIV:Crestie|20gL:Leos|10g:Pearl Fighter|5g:Betta|5gChi:Spark Gourami/Badis|5g:ADF|2.5g:Betta|2.5g:Betta|