Originally Posted by Breakthecycle2
What should the weekly water change be? Gallon wise?
Depends on your
system... if you've got a properly stocked tank with a quality skimmer & well established refugium keeping your excess bad nutrients in check, then you're more doing water changes for good nutrient replenishment than waste export. At that point, 10% weekly should be fine, which in your case would be 12 gallons.
If you're overfeeding a heavily stocked tank, then you're going to require much larger changes more often...... Testing your system is the best way to determine what you need to do.