Equilibrium in 7-8 weeks vs 50 is a wee bit of an improvement...
Reading through this again naturally brought me back around to some of the many dialogs that have taken place regarding filtration systems, water exchange/flow rates, TT's vs. BS, etc...
Finding that point of a healthy equilibrium and maintaining it in a continuum seems to be the sticking point for most ponders. My own preference is for a continual trickle, but no matter what, the need to dump settlement does alter the dilution ratio from time to time, as does evaporation rates changing throughout the year. Add to that the fact that during the peak evaporation season we are also feeding at the heaviest rate it is small wonder that so many seem to experience 3 seasons of water issues.
Season 1. Dead filters and a pond full of leaves, etc... every spring and the associated "new pond syndrome", aeromonas outbreaks, etc... being repeated annually.
Season 2. Mid-summer nights bad dream. Heavy feeding with unstable oxygen levels caused by a 2nd round of green water due to inadequate filtration, little or no fresh water exchange, day/night ph swings, etc...
Season 3. Feeding too much as summer turns to fall, thereby re-creating a polluted pond just in time to shut down filtration and put the fish to bed for the winter...
While these scenarios may not hold true for most of the ponders on this forum, it is one that is constantly repeated on some. Following an intelligent and rational program of water maintenance as Mike has described would save most ponders the yearlong frustration of constantly battling for "equilibrium" and only finding it 2 or 3 weeks at a time...