Phosphate reservoirs in the aquarium

[Tom Reefer]

Hi Randy, I have a 20 gallon nano reef that’s been very successful. More recently Ive been adding some SPS corals. I understand that my phosphate levels must be quite low in order to create good growth and health of SPS corals. I’ve recently began to attempt to lower phosphate without using any chemical use. I’ve had a 1” sand bed that I’ve neglected to vacuum and I believe that has caused my phosphate levels to be as high as they are. They are about 0.5. I noticed after I vacuumed the sand bed, my phosphate level dropped dramatically, 0.09. However, within 24 hours, it began to rise again quite substantially. Is it possible that I need to continue to vacuum the sand bed? Could there be more substantial phosphate left in this reservoir, or could it be coming from somewhere else, live rock/ feeding. I can’t test my live rock, because the pieces are cemented together in one large piece. My thought on feeding is, it can’t possibly be raising it up that much in 24 hours. I’ve read your article from time past on phosphate, but I thought there might be new information on this topic. Thanks Tom

 

[Val Shebeko]

F

 

[Randy Holmes-Farley Verified Community Expert]

Most of the inorganic phosphate in a reef tank is bound to the surface of calcium carbonate rock and sand. It is in equilibrium with what is in the water and acts as a big reservoir.