I have a 75 g. planted freshwater tank, established for years. Suddenly about 2 weeks ago, a heavy white scum formed on the water surface. The filter only...
In doubt of what's causing this, I would be doing partial water changes every day, if it's soap or something like that it should dilute by doing so. Test for...
I'm wondering if this could be a protein build-up???? Have you changed feeding habits or products? Also what type of filtration especially any forceful air...