Approximately four months ago I started two small acrylic freshwater tanks.
One 2.5 gallon with a betta. One 7 gallon with six glo-fish (zebra danios).
The 2.5 has a snail. The 7 gallon has four snails.
To this day the 2.5 is always crystal clear. The 7 gallon is *never* crystal clear and has a ridiculous amount of algae/black stuff collected in the filter. The filter has to be changed every two weeks and is always "loaded" with black-ish gunk.
What in the world am I doing wrong?