This is very true. The trick to not killing off your beneficial bacteria is to pre dechlorinate the water then pump it in that way you dont kill all the bacteria on your decor/tank.jschall;3959002; said:You can do 95% water changes without affecting the BB.
Bigger water changes are more effective (meaning, a 50% every 2 weeks is better than a 25% every week)
I think if you used a python right from the tap for a 95% fill you would be asking for some BB die off as well as fish stress possibly death.