So I got my order of RCS, I didn't realize how small they were gonna be. So I ended up taking my 3 female guppies and putting them into my 10 gallon tank. After doing this I started getting an oil film on the top of my tank. Maybe from no water movement? I did a small water change and that didn't seem to help at all. I was thinking maybe an airstone would end up helping? The only thing I worry about is that I have sand on the bottom, and last thing I want is for the sand to go up into my filter killing it. I do have a small sponge stuck to it. Is there another way of getting rid of this nasty film other than what I mentioned?