Recycling SPS?

[crimper]

I used to put crushed corals on my HOB as a filter media on my decommissioned 20G nano, I noticed that the crushed corals depletes as times goes by. I think that they react with the trapped CO2 in foam media and also CO2 from the water itself releasing Ca and Alk back in the water.

I didn't noticed PO4 spike. Maybe it's worth doing some experiments with that Walter