How are your hoses?? are they really brown and dirty?? (I would drain them, take them off and run a cloth or something through them. You could tie a nut or something to some string and the other to the cloth and then drop the nut through and pull the cloth through) If not maybe replace the hosees.. Have you cleaned the impellor lately?? Just some suggestions..
only 6 months old... shouldn't be dirty hoses. I would also check the impeller or how tight the connections are with the hoses. I have a rena, over 1 yr old and still has great pressure. Do you have the flow limiter on? Just a cople thoughts.