like Dr.Case...my waterchanges are small,and frequent.. basically the water it takes to flush my filter. for the basement pond, i just turn off the pump and open the flush valve. it drains into our sump pump basin, and gets pumped out to the sewer. the whole thing takes less than 10 minutes. i have another 55 gal barrel in the basement that i fill with water and dechlorinate. as soon as its emptied, so it sits for the time ( 4 or 5 days) between flushes and acclimates to the basement temps. this water gets pumped into the basement pond to replace the flushed water. outside, i just i add around 50 gals of dechlorinated water every 4 or 5 days. i just use the same barrel as i use in the basement. with my prefilters, i need not flush my filter but a couple times a summer.... the people who have problems because of water changes. have them because they do too large of a change. frequent small water changes are much better. they cause less stress on the fish. they have less of a "sudden" impact on water chemistry. but water changes do alot of good... they replace trace minerals, and electrolites. they dilute, toxins,tannins,DOCs, and even pheromones that build up in the system. when pheromones build up they can cause aggressive behavior, and even shut down fish immune systems. the heavier the fish load and bio loads the more beneficial waterchanges are.
