I have several freshwater aquariums of following volumes:
- one 5 gallon
- one 10 gallon
- two 20 gallon
- one 29 gallon
- one 55 gallon
and an outdoor 300 gallon pond. Aside from the pond, I started with one community tank and now have a rescue tank, a neon breeding tank and the others are holding tanks for my babies at different stages (the neon tetras, balloon mollies and fancy guppies just won't stop reproducing!) All of my tanks get weekly partial water changes, get tested with a Master Test Kit once a week, but vary in salinity, purpose and decoration - natural versus artificial plants.
All tanks have natural gravel except one. One of my 20 gallon tanks has black gravel. I have no live plants in this tank, just two Pygmy Cory cats and guppy babies. It's regularly cloudy, and yet the maintenance I perform on it is the exact same as the rest. I have zero fish loss, and my ammonia and nitrites never reach higher than 0.25 ppm and my nitrates never reach 5.0 ppm (usually test results between 0 and 5). All of my tanks have been running for 4+ years and I haven't had a fish die in 2 years, and that was because I accidentally smashed a baby guppy with my gravel vacuum during a water change.
I change my carbon every other month in all my other aquariums because I prefer to retain as much good bacteria as possible, but 3 months ago started changing this tanks once a month, as directed on the packaging hoping to increase clarity, but no change.
It's aggravating because it's an eyesore and I would know EXACTLY what to do if it were caused by shock, but it's not. Could this be because of the black gravel? It was rinsed before the tank was set up, but that was forever ago. I have concerns about doing a 100% water change and starting from scratch since my fish are in such great shape. Has anyone had this happen to them before, where all parameters were fine but the tank was cloudy? I'm stumped! Any help would be greatly appreciated.
Sorry for the book, I just wanted to put as much background info as possible.