I have been using the fluval 404 for the past 8 weeks on my 75gal tank. I set it up with the outflow suspended a quarter length under the water surface.
I encountered a small problem with water cloudiness and I think I know why. If this makes any sense let me know.
Since the outflow is submerged, there is absolutely no surface agitation at all.
My water from the tap is quite cloudy and clears up in a standing glass after a few minutes.
My 30gal usually clears up within a few hours. The 75gal seems to take almost a week or more.
My theory is that the cloudiness is due to having no surface agitation (as compared to the tank that does. Could it be due to all the water remaining in a "closed" system?
methods are the same for each tank, both are done at the same time.
What do you guys think?