Like Phosban, Rowaphos is made of ferric oxide hydroxide rather than aluminum oxides. Aluminum oxides does remove phosphate, but isn’t ideal for a reef tank because it often leaves enough phosphate in the water for nuisance algae and it contains aluminum.
Rowaphos is wet with a caviar-like appearance. The manufacturer recommends keeping the material moist and the container tightly closed.
Rowaphos is really effective at lowering phosphate levels in a reef tank and can reduce them to natural seawater levels. Howerver, I tried it once and see no (or maybe little) difference in effectiveness of the two leading brands: Phosban and Rowaphos. Both product can be used depending on price and availability.
Flow rate is important. It will not receive enough flow by having it in a media bag. Not enough flow will cause it to “clump up” making it less efficient. For that reason, you should definitely get a reactor. A Phosban reactor will do the job. A reactor allow you to push about 80-90 GPH through the Rowaphos which is I think the best flow rate.