Algea and oil slick?

[StevenD]

Hello,

I have a Walstad planted aquarium that was doing fine for a couple of years then I got this recurring slick on the top of the tank and this dark algae. At least, I think it is algae.

I have tried removing the oil slick with carbon and filtration, but it comes back. I don't know where the slick is coming from. I have no idea what to do about the algae.

Hopefully the pictures are good enough to show what this stuff is.

 

[itiwhetu]

Have you an air stone on this tank. It will help to break up the surface tension. And allow better gas exchange. Between the tank and the atmosphere.

 

[StevenF]

It's often calle a protean film It is typically caused harmless bacteria floating on the surface of the water. It is typically solved with increased surface agitation of the water. On larger tanks the filter intake is attached to the hose that is positioned just below the water surface. The film is then pulled into the filter

 

[StevenD]

Thank you for the advice about the oil slick. I will try the air stone idea. Any ideas on how I can remove the black algae on the plants or whatever that stuff is?


Update: I added a couple of air stones and that got rid of the protean film. The black algae remains though...