Ok first off you need to get some carbon in the tank in a filter bag or in a reactor. Second you need to do a series of water changes, the bigger the better. Not sure what you have in your tank, a skimmer would really help too but not sure your running one.
likely the film is from the live rock addition and the death. Doing the above will help dilute and clean up any toxins present.
29g Mixed Reef, 150w 14k Phoenix MH w/ Moonlights, Reef Octopus BH1000 HOB Skimmer, Ecotech Vortech MP10es, ReefKeeper Lite (Plus), PH Probe, Temp Probe, ATO, Carbon/GFO Reactor.