I made a berliner weisse in november that I am finally getting around to kegging. It never ended up getting sour, so I added a few ounces of lactic acid to get it where I wanted it. I racked it onto some raspberry puree a few weeks ago a strange film on top of the beer that I had never seen before. It still tastes fine now and I have it cold crashing. I was wondering if it would be ok to rack onto some campden tablets in the keg to kill off whatever might be in it.