What is the Clear film that built up in my fish tank?

So i had a fish tank set up, and before i moved (for about a month) i gave my fish to someone and didnt do anything about the water (I know its bad, but it was so hectic moving i didnt have time). Anyway, i just restarted my tank at my new place and i have been trying to cycle the tank. All appropriate chemicals have been added to start a new tank, but now there is a clear "film" over every surface in the tank. It also looks like there are hundreds of "Particles" floating around in the tank. All the levels (Ph, ammonia, nitrate and nitrite) are within normal range, and the tank has been thouroughly scrubbed before i readded water. I tried to put small fish in there to test out the water and they all died within 24 hours. Im at a loss for whats going on, so if anyone can please help me, i really want my fish back...