nope.. i do 20% water changes on my 500 gallon system every 2 weeks, and have no problem. my outlet runs directly into the piping for the septic system...been running like this for the last year and half,,, no problems yet.. what i have noticed is that when i used to dump the water in my driveway, the plants , especially the trees and shrubs started to burn out..so i just stick to using the septic system... i have thought about using the septic system bacteria regenerator from time to time, but have never had to use it..