Surface Film

Joined
17 Mar 2012
Messages
1,345
Location
Dorset
I’m just starting an unheated and unfiltered 10L Nano. The only occupants until this evening was some Tetra Active Substrate and four Moss balls. I bought some Spider wood to put into the tank today and when I took the cover glass off I noticed quite a bit of surface film. I’m sure the culprit must be the substrate as the Moss ball were happily sitting in a vase for a week without any problems. Anyone had this problem before? I did thoroughly rinse the substrate with hot water before putting it in.
 

Simon Cole

Member
Joined
25 Dec 2018
Messages
469
Location
Buckingham
Yes this is very common in new and old tanks. It is almost guaranteed without flow. There is a dusty green algae that likes to form a film. You can also get patchy-shiny and sticky bacterial films. At the moment I have a dusty film in one of my tanks, but I wouldn't like to guess at the cause. It's all quite natural. Drop a clean paper towel on the surface and lift it away from the centre, or get a skimmer. Some people will say this is due to the chemical balance, but really many natural systems are unbalanced and work in cycles. I would not look at this as something that should be controlled. Daphnia, or even better cyclops, would be a very sensible livestock choice. Alternatively, a paramecium strain might work if you can identify the microbial cause. Less common are scums and chemical films. They are surprisingly common in limestone fenland springs and in glacial melt-water.
 
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