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If you belive it to be particulate instead of bubbles, then you might try a 100 Micron sock on the water entry to the sump. Get 2 or 3 and for the initial begginning, replace them ever 2 days (even if not overflowing).
If nothing in the tank is showing signs of stress, I wouldn't go so far as to drain and start over.
Does it appear milky and "swirl" across the surface?
I've run into issues with the Caribsea "arag-alive" sand in the past. The bags have experiation dates on them, and apparently I didn't notice a bag I had purchased had passed that date. Even tho the bag says not to, I still rinse it in tank water before use because I'm convinced the problem I had was coming from the sand. Just my two cents from past experience.