Hi I’m looking at burning the Python no spill kit for water changes. I currently do a 10% water change manually with buckets. I’m new to having a sump and understand that I should probably siphon that out once in awhile. The question is if I’m using the Python and it’s attached to a faucet how do I know I’m doing a 10% water change? I know if I’m just doing my DT then I could draw a line where I know it’s 10% but what if I siphon out the sump? Maybe this is a stupid question !