I am trying to find what my % is for what my water change should be....I am just trying to figure if I need to add in my sump volume or not. I have a 120g and about 25-30g in my sump.
What you can do is when you shut off the pump on your tank to pump out your water from your sump, pump it the first time into 5 gallon buckets (I would only do like 2-3 if you have a small bio load) then when it's pumped out mark the water level on your sump with a marker on the glass. This way next time when you do a water change when the water level hits your marker you know it's 10, 15, etc gallon.
That's how I did mine also. I have a 200+ gal with 2 - 30gal sumps, and I change 50gal at the end of the mth. I bought one of those brothers label makers (Staples) and put markings all over my sump - "regular water level", "50Gal mark", "Water level-main pump off".........etc. Also used it to label every item and plug. Easier for me and my wife. Made live very easy. I dump water back into the display though, that way, the new water is mixed with a larger volume of water. When it overflows and fills back up the sump, I just turn back on the main pump.
I know it's an old thread, but I had a question.
My setup has a total system volume of 112 gallons (includes the display and the sump).
However, the sump obviously doesn't run full to the top and the tank has rock/sand in it, significantly reducing how much actual water is running through the system... Should we be calculating off the total possible system volume, or trying to ballpark how much actual water is in the system after deducting rock/sand/sump level and basing our percentage off that?