What does X% water change mean?

[Aquarist007]

Originally posted by scolley
WOW! I said I was not going to post any more on this. But the good capn's response helped me understand WHY I'm getting some of the responses I'm getting!

PLEASE take a look at my original post. I am NOT asking how much water to change, not for you, not for me, don't wanna know right now.

What I AM asking is when you say "I'm changing "X" percent... " that is X percent of WHAT? X% of your tank volume? X% of the nominal volume of your tank? X% of the total volume of all the the water in your system?

That X is a percentage of SOMETHING. What is that something?

Thanks. Now I'm through.

x% of total total volume of all the water in my system

Scolley it should be total water in the system for calculating just about everything except for internal flow which is gph of the tank volume itself.