After you put the new rowaphos into the FR, run tap water into it until the water turns clear. That will rinse the rowaphos properly.
As for water turning yellow in long run that is caused by not using GAC Nothing to do with rowaphos.
Too many fine particle flying ard is due to too high flow rate in the FR so reduce your flow until the media are just lift a little will do the trick. No need for them to be dancing like in disco.
See your post, 9 months w/o activated carbon so that's why your tank water turn yellowish.
http://www.sgreefclub.com/forum/index.php?...=0entry332008