Oily-looking film in established 10G

Yesterday I noticed an oily-looking film on top of the water in my established 10G aquarium. I've never seen anything like this before, so did some research. It seems to be 'normal', with various causes - (low surface movement, some foods, dirty water, oils from my skin, etc). Water changes seemed to be the suggestion to get rid of it. I tested my water, and it was perfect. I skimmed the top with a paper towel to get most of it out, then went on and did a water change as well. Well, this afternoon when I came home from work, it was back. The tank has a mixture of sand/gravel, and is moderately planted. It also contains a young betta, 2 small mystery snails, and 4 ghost shrimp. I have a Whisper 30 HOB filter that normally goes at full blast - the betta doesn't have a problem with it at all. But there are parts of the tank that seem 'still' (no plants gently waving). The filter is good for up to a 30G tank, and the water surface seems to agitate fairly well. I haven't changed the type of food I feed my betta. The only thing different I can think of is that I have started to feed small pieces of algae wafers for the shrimp once-twice a week. I break them into minuscule pieces, and give 4 - one for each shrimp - about the size of a pinhead. Could this be what is causing the film? I've been feeding it for the last few weeks (maybe 4 times?), but only saw the film yesterday. Not sure if this could be it or not, as I did change the water and siphoned out the gravel pretty well...I thought that would take care of it, but it's back the very next day. The tank readings are below, any ideas on what I can do to get rid of it besides daily water changes? I hate to do that to the inhabitants if it's not necessary, and since the water readings are fairly optimal I don't want to mess anything up. But I worry about the betta coming up to breathe with that film on the surface. Thanks in advance for any advice.

pH-7.6
Ammonia - 0 ppm
Nitrites - 0 ppm
Nitrates - 10 ppm
Phosphorus - 0 ppm

 

Annie, is this a different tank then the one with high nitrites?

It does sound like bio-film. The easiest way to get rid of it is to allow more spashing from your whisper filter. It is an hob or an internal? Try and position it so the water actually breaks the surface of the water. This is easy to get rid of if you do that.

 

This is a different tank than the one with high nitrites. The readings on this one are great. The filter is a HOB, and it is already on full blast. It's positioned on one side of the tank, do you think it might make a difference if I moved it to the middle of the tank instead? I keep the tank filled, should I lower the water level?

 

I have an idea now that you have mentioned this tank. Take the filter, snails and shrimp from the re-cycling tank and put them in this cycled tank for a full week. Then move them back over and you should be cycled again and be able to add in the betta you want. Make sure you do 100% water change on the cycling tank before adding the filter and new betta back in.

On this tank yeah it might help to move the filter and let the water level lower just a tiny bit, enough so it spashes.

 

you can also use a siphon to skI'm the top when doing water changes. A few of my tanks have had this before and it seems nothing I do will make it go away . Then one day its just gone

 

I used to get that when my males would make bubble nests, I agree about moving the filter and lowering water a tad. Of you want to keep underwater current in check for the betta, you can always just put decor or plants right under the flow.