Why can’t I keep SPS?!

[92Miata]

Maybe I’m wrong here but isn’t it the opposite? The dry rock should be soaking up phosphates until it hit max saturation which would then make the soluble phosphate levels even higher since the amount getting bound drops. Older tanks are also generally higher in nutrients on average.

Rock doesn't have a max saturation (it does, but its way higher than your corals would live through)- there is an equilibrium point related to the concentration in the water. A tank at .05 will have significantly less phosphate in its rock than a tank at .5.


Older tanks are often higher in nutrients because they have way more surface competition, way more corals, and can keep more food in the water without having algae issues. Most of these older tanks are feeding more in a single feeding than newer tanks feed in a week.