Hello fellow hobbyist, I recently have been having some problems with my son's tank, his tank is getting some kind of chemical film or residue on the top of the water.
His tank is planted, although the plants are just sprouting from bulbs and i have Floramax substrate capped with black tahitian sand, i have never had this issue before and don't know what could be causing this. If anyone can help i would appreciate it, and i will try to put up some pics.
break the water surface, it is a biofilm, and you can break it by creating water waves, rain/spray bar, aeration etc.
Other than that, you can use newpaper, papertowel, or wrap on the surface, absorb, and take out but it is temp.
It will come back. one thing you can do is get one of those little nano filters, and discard the filter part of it to use the pump as a powerhead, let it break the surface of the water a little and it will not come back.
all you need is surface agitation. air stone, power head, hob filter, spray bar, skimmer, whatever. i stuck an empty fert bottle under the u-shape on my spraybar so that the spraybar sits at a 45' angle and the first vent or two are above the water surface. problem solved.