I base my water change schedule using nitrate as an indicator of need to change.
My target nitrate number is 5ppm.
And I have found to keep my tanks at 5 ppm or below, I need to do a 30-40% water change every other day on my 180 gal, with heavily planted 125 gal sump/refugium, in total containing seven 5 -7" fish, and a bunch of shrimp in th refugium.,
Everyones tank, feeding regime, and filtration is different, there is "no" one size fits all.
My target nitrate number is 5ppm.
And I have found to keep my tanks at 5 ppm or below, I need to do a 30-40% water change every other day on my 180 gal, with heavily planted 125 gal sump/refugium, in total containing seven 5 -7" fish, and a bunch of shrimp in th refugium.,
Everyones tank, feeding regime, and filtration is different, there is "no" one size fits all.