Green film on water surface...

Discussion in 'General Planted Tank Discussions' started by bugs, 24 Feb 2008.

  1. bugs

    bugs Member

    Green film on water surface - good or bad?

    Tank = 60cm, no CO2, no ferts (occasional splash of Leafzone, just to use up what's left in the bottle). It's psuedo El Natural in so far as I've switched off the CO2 and stopped adding ferts.

    The film is not posing any problems as the moment, I just wondered what opinions would be...
  2. George Farmer

    George Farmer Founder Staff Member

    "Bad" if it blocks too much light, or compromises gaseous exchange.

    Other than that, I doubt it will have any negative effect.

    Scum is a fact of life for some set ups.

    If you don't mind the look of it, then I don't see it as an issue.
  3. Themuleous

    Themuleous Member

    Aston, Oxfordshire
    I have this on one of my tanks. I'm used to the while oily film but never had a green film before. I use kitchen towel to get it off but it soon grows back. If you find a way of getting rid of it let me know!! I do notice that it blocks quite a bit of light out but its a low light tank anyway so its not a big problem.

    As its only on the surface its never been much of a worry, i can really see it and so long as it doesn't invade further down into the tank I'm happy to leave it be. Unless of course I can find a way of ridding the tank of it completely.

  4. Vase

    Vase Member

    Would a surface skimmer not work? Obviously you'd need an external to work one though.

  5. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Chicago, USA
    Here's another perspective: Surface film can be an indication of starvation. The plants are leeching proteins, lipids/fatty acids and enzymes into the water column as cell structure deteriorates. The withdrawal of CO2 and nutrients could easily have precipitated this. If you withdrew these nutrients without also lowering the lights that would make matters worse. It may be that after a few weeks the plants will adjust to the lowered nutrient levels and will stop leeching. To answer the question though, in my opinion scum is never a good sign whether green, white or brown.

  6. Ed Seeley

    Ed Seeley Member

    I get green algae growing in a film on the water's surface of one of my Apistogramma breeding tanks. It's a very different beast to the more usual surface film of oils/organic compounds. It does no harm to the fish or the water quality and I simply skim it off regularly. Positioning the outlet to ripple the surface gets rid of it too.
  7. bugs

    bugs Member

    To add some more info in view of the comments so far...

    The light levels were reduced in line with the removal of CO2 and ferts.

    Since the removal of CO2 and ferts I've watched the film appear and then disappear again. It's just recurred again recently.

    No sign of the plants degenerating but I am watching closely to see what happens.

    Currently I'm planning to avoid mechanical removal, preferring to find out how it cleared up last time and see if I can replicate those conditions - that is, of course, whilst continuing to monitor to see if it's presence indicates positive, negative, or neutral conditions. Or possibly cyclical/transient conditions that should simply be allowed to occur.

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