I think that is the key, to be consistant and do a flush around 1x/month till you have 3 clear in a row. It is like digging through hard dirt, the more time you have in between a flush the more time the "dirt begins to harden". Just keep at it and if you are considering yourself to be on your 5th flush than we are on a similar page, I am doing my 5th flush this upcoming weekend. It is kind of impowering.